0 Preparation

The following packages need to be installed:

Show the code

# install CRAN packages
pkg_install =   c("ggplot2", "tibble", "tidyr", "forcats", "purrr", "prismatic", "corrr",
    "cowplot", "ggforce", "ggrepel", "ggridges", "ggsci", "ggtext", "ggthemes",
    "grid", "gridExtra", "patchwork", "rcartocolor", "scico", "showtext",
    "shiny", "plotly", "highcharter", "echarts4r", "hrbrthemes")
install.packages(pkg_install)

In which:

ggplot2: part of the tidyverse, implementing the grammar of graphic;
tidyverse:
- tibble: mordern data frames;
- dplyr: data wrangling;
- tidyr: data cleaning;
- forcats: handling factors;
corrr: correlation matrices;
cowplot: composing ggplots;
ggforce: sina plots and other cool stuffs;
ggrepel: nice text labeling;
ggridges: rigde plots;
ggsci: nice color palettes;
ggtext: advanced text rendering;
ggthemes: additional themes;
grid: creating graphical objects;
gridExtra: additional functions for grid graphics;
patchwork: multiple panel plots;
prismatic: minipulating colors;
rcartocolor: great color palettes;
scico: perceptional uniform palettes;
showtext: custom fonts;
shiny: interactive applications;
charter, echarts4r, ggiraph, highcharter, plotly: interactive visualization.

We also need to install devtools:

Show the code

# install from GitHub since not on CRAN
install.packages('devtools')
devtools::install_github("JohnCoene/charter")

1 The Dataset

I was using the dataset: “National Morbidity and Mortality Air Pollution Study (NMMAPS)”

Install the readr first:

Show the code

install.packages('readr')

1.1 Import data

The :: here call the namespace and can be used to access a function without loading the package.

Show the code

library(readr)

Warning: package 'readr' was built under R version 4.4.3

Show the code

chic <- readr::read_csv("https://cedricscherer.com/data/chicago-nmmaps-custom.csv")

Rows: 1461 Columns: 10
── Column specification ────────────────────────────────────────────────────────
Delimiter: ","
chr  (3): city, season, month
dbl  (6): temp, o3, dewpoint, pm10, yday, year
date (1): date

ℹ Use `spec()` to retrieve the full column specification for this data.
ℹ Specify the column types or set `show_col_types = FALSE` to quiet this message.

view some data:

Show the code

tibble::glimpse(chic)

Rows: 1,461
Columns: 10
$ city     <chr> "chic", "chic", "chic", "chic", "chic", "chic", "chic", "chic…
$ date     <date> 1997-01-01, 1997-01-02, 1997-01-03, 1997-01-04, 1997-01-05, …
$ temp     <dbl> 36.0, 45.0, 40.0, 51.5, 27.0, 17.0, 16.0, 19.0, 26.0, 16.0, 1…
$ o3       <dbl> 5.659256, 5.525417, 6.288548, 7.537758, 20.760798, 14.940874,…
$ dewpoint <dbl> 37.500, 47.250, 38.000, 45.500, 11.250, 5.750, 7.000, 17.750,…
$ pm10     <dbl> 13.052268, 41.948600, 27.041751, 25.072573, 15.343121, 9.3646…
$ season   <chr> "Winter", "Winter", "Winter", "Winter", "Winter", "Winter", "…
$ yday     <dbl> 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18…
$ month    <chr> "Jan", "Jan", "Jan", "Jan", "Jan", "Jan", "Jan", "Jan", "Jan"…
$ year     <dbl> 1997, 1997, 1997, 1997, 1997, 1997, 1997, 1997, 1997, 1997, 1…

Show the code

head(chic,10)

# A tibble: 10 × 10
   city  date        temp    o3 dewpoint  pm10 season  yday month  year
   <chr> <date>     <dbl> <dbl>    <dbl> <dbl> <chr>  <dbl> <chr> <dbl>
 1 chic  1997-01-01  36    5.66    37.5  13.1  Winter     1 Jan    1997
 2 chic  1997-01-02  45    5.53    47.2  41.9  Winter     2 Jan    1997
 3 chic  1997-01-03  40    6.29    38    27.0  Winter     3 Jan    1997
 4 chic  1997-01-04  51.5  7.54    45.5  25.1  Winter     4 Jan    1997
 5 chic  1997-01-05  27   20.8     11.2  15.3  Winter     5 Jan    1997
 6 chic  1997-01-06  17   14.9      5.75  9.36 Winter     6 Jan    1997
 7 chic  1997-01-07  16   11.9      7    20.2  Winter     7 Jan    1997
 8 chic  1997-01-08  19    8.68    17.8  33.1  Winter     8 Jan    1997
 9 chic  1997-01-09  26   13.4     24    12.1  Winter     9 Jan    1997
10 chic  1997-01-10  16   10.4      5.38 24.8  Winter    10 Jan    1997

3 The `{ggplot2}` package

A ggplot is built up from a few basic elements:

Data;
Geometries geom_: the geometric shape (hình dạng) that will represent the data;
Aesthetics aes_: aesthetics (thẩm mỹ) of the geometric or statistical objects, such as postition, color, size, shape, and transparency;
Scales scale_: map between the data and the aesthetics dimensions (ánh xạ từ dữ liệu đến đồ thị), such as data range to plot width or factor values to colors;
Statistical transformations stat_: statistical summaries (thống kê) of data, such as quantitles, fitted curves, and sums;
Coordinate system coord_: the transformation used for mapping data coordinates into the plane of the data rectangles (hệ tọa độ);
Facets facet_: the arrangement of the data into a grid of plots;
Visual themes theme(): the overall visual defaults of a plot, such as background, grids, axes, default typeface, sizes and colors (tông).

Each of above elements can be ignored, but can be also called multiple times.

4 A default `ggplot`

Load the package for ability to use the functionality:

Show the code

library(ggplot2)

Warning: package 'ggplot2' was built under R version 4.4.3

Show the code

# library(tidyverse) # can also be imported from the tidy-universe!

A default ggplot needs three things that you have to specify: the data, aesthetics, and a geometry.:

starting to define a plot by using ggplot(data = df);
if we want to plot (in most cases) 2 variables, we must add positional aesthetics aes(x = var1, y = var2);

Notice that data was mentioned outside the scope of aes(), while variables are being mentioned inside aes().

For instance:

Show the code

(g <- ggplot(chic, aes(x = date, y = temp)))

Just a blank panel, because ggplot2 does not know how we plot data ~ we still need to provide geometry. ggplot2 allows us to store the ggobject to a variable inside the environment - in this case, g - which can be extended later on (by adding more layers). We can print out the plot to the R interactive by putting all inside the ().

We have different geometries to use (called geoms because each function usually starts with geom_). For e.g., if we want to plot a scatter plot.

Show the code

g + geom_point()

also a line plot which our managers always like:

Show the code

g + geom_line()

cool but the plot does not look optimal, we can also using mutiple layers of geometry, where the magic and fun start.

Show the code

# it's the same if we write g + geom_line() + geom_point()
g + geom_point() + geom_line()

4.1 Change properties of geometries

Turn all points to large fire-red diamonds:

Show the code

g + geom_point(color = 'firebrick', shape = 'diamond', size = 2)

Note

ggplot2 can unsderstand when we use color, colour, as well as col;
We can use the default color or hex, or even RGB/RGBA with rgb(). For example:

Show the code

g + geom_point(color = "#b22222", shape = "diamond", size = 2)

Show the code

g + geom_point(color = rgb(178, 34, 34, maxColorValue = 255), shape = "diamond", size = 2)

4.1 Replacing the default `ggplot2` theme

Calling eg theme_bw() using theme_set(), all following plots will have same blank’n’white theme.

Show the code

theme_set(theme_bw())

g + geom_point(color = 'firebrick')

theme() is also a useful function to modify all kinds of theme elements (texts, rectangles, and lines). Refer this page for the full list.

5 Axes

5.1 Change axis titles

Use labs() to assign character string for each lable.

Show the code

ggplot(chic, aes(x = date, y = temp)) +
    geom_point(color = 'firebrick') +
    labs(x = 'Year', y = 'Temperature (°F)')

Can also using xlab() and ylab():

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "firebrick") +
  xlab("Year") +
  ylab("Temperature (°F)")

Not only the degree symbol before F, but also the supper script:

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "firebrick") +
  labs(x = "Year", y = expression(paste("Temperature (", degree ~ F, ")"^"(Hey, why should we use metric units?!)")))

5.2 Increase space between axis and axis titles.

Overwrite the default element_text() within the theme() call:

Show the code

ggplot(chic, aes(x = date, y = temp)) +
    geom_point(color = 'firebrick') +
    labs(x = 'Year', y = 'Temperature (°F)') +
    theme(axis.title.x = element_text(vjust = 0, size = 30),
         axis.title.y = element_text(vjust = 2, size = 30))

vjust refer to vertical alignment. We can also change the distance by specifying the margin of both text elements.

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "firebrick") +
  labs(x = "Year", y = "Temperature (°F)") +
  theme(axis.title.x = element_text(margin = margin(t = 10), size = 15),
        axis.title.y = element_text(margin = margin(r = 10), size = 15))

t and r in the margin are top and right. Margin has 4 arguments: margin(t, r, b, l). A good way to remember the order of the margin sides is “t-r-ou-b-l-e”.

5.3 Change aesthetics of the axis titles

Again, we use theme() function and modify the axis.title and/or the subordinated elements axis.title.x and axis.title.y . Within element_text(), we can modify the default of size, color, and face.

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "firebrick") +
  labs(x = "Year", y = "Temperature (°F)") +
  theme(axis.title = element_text(size = 15, color = "firebrick",
                                  face = "italic"))

the face argument can be used to make the font bold, italic, or even bold.italic.

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "firebrick") +
  labs(x = "Year", y = "Temperature (°F)") +
  theme(axis.title.x = element_text(color = "sienna", size = 15, face = 'bold'),
        axis.title.y = element_text(color = "orangered", size = 15, face = 'bold.italic'))

You could also use a combination of axis.title and axis.title.y, since axis.title.x inherits the values from axis.title. Eg:

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "firebrick") +
  labs(x = "Year", y = "Temperature (°F)") +
  theme(axis.title = element_text(color = "sienna", size = 15),
        axis.title.y = element_text(color = "orangered", size = 15))

One can modify some properties for both axis titles and other only for one or properties for each on its own:

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "firebrick") +
  labs(x = "Year", y = "Temperature (°F)") +
  theme(axis.title = element_text(color = "sienna", size = 15, face = "bold"),
        axis.title.y = element_text(face = "bold.italic"))

5.4 Change aesthetics of axis text

Similar to the title, we can change the appearance of the axis text (number indeed) by using axis.text and/or the subordinated elements axis.text.x and axis.text.y.

Show the code

ggplot(chic, aes(x = date, y = temp)) +
    geom_point(color = 'firebrick') +
    labs(x= "Year", y = expression(paste("Temperature(",degree ~ F, ")"))) +
    theme(axis.text = element_text(color = "dodgerblue", size = 13),
         axis.text.x = element_text(face = 'italic'))

5.5 Rotate axis text

Specifying an angle help us to rotate any text elements. With hjust and vjust we can adjust the position of text afterwards horizontally (0 = left, 1 = right), and vertically (0 = top, 1 = bottom).

Show the code

ggplot(chic, aes(x = date, y = temp)) +
    geom_point(color = 'firebrick') +
    labs(x= "Year", y = expression(paste("Temperature(",degree ~ F, ")"))) +
    # 50 means 50 degrees, not % =)))
    theme(axis.text.x = element_text(angle = 50, vjust = 1, hjust = 1, size = 13))

5.6 Remove axis text & ticks

Rarely a reason to do this but this is how it works.

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "firebrick") +
  labs(x = "Year", y = "Temperature (°F)") +
  theme(axis.ticks.y = element_blank(),
        axis.text.y = element_blank())

If you want to get rid of a theme element, the element is always element_blank.

5.7 Remove Axis Titles

We could again use element_blank() but it is way simpler to just remove the label in the labs() (or xlab()) call:

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "firebrick") +
  labs(x = NULL, y = "")

Note that NULL removes the element (similarly to element_blank()) while empty quotes "" will keep the spacing for the axis title and simply print nothing.

5.8 Limit axis range

Some time you want to take a closer look at some range of you data. You can do this without subsetting your data:

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "firebrick") +
  labs(x = "Year", y = "Temperature (°F)") +
  ylim(c(0, 50))

Warning: Removed 777 rows containing missing values or values outside the scale range
(`geom_point()`).

Alternatively you can use scale_y_continuous(limits = c(0, 50)) (subsetting) or coord_cartesian(ylim = c(0, 50)). The former removes all data points outside the range while the second adjusts the visible area (zooming) and is similar to ylim(c(0, 50)) (subsetting).

5.9 Force plot to start at the origin

Show the code

chic_high <- dplyr::filter(chic, temp > 25, o3 > 20)

ggplot(chic_high, aes(x = temp, y = o3)) +
  geom_point(color = "darkcyan") +
  labs(x = "Temperature higher than 25°F",
       y = "Ozone higher than 20 ppb") +
  expand_limits(x = 0, y = 0)

Using coord_cartesian(xlim = c(0,NA), ylim = c(0,NA)) will lead to the same result.

Show the code

chic_high <- dplyr::filter(chic, temp > 25, o3 > 20)

ggplot(chic_high, aes(x = temp, y = o3)) +
  geom_point(color = "darkcyan") +
  labs(x = "Temperature higher than 25°F",
       y = "Ozone higher than 20 ppb") +
  coord_cartesian(xlim = c(0, NA), ylim = c(0, NA))

But we can also force it to literally start at the origin!

Show the code

ggplot(chic_high, aes(x = temp, y = o3)) +
  geom_point(color = "darkcyan") +
  labs(x = "Temperature higher than 25°F",
       y = "Ozone higher than 20 ppb") +
  expand_limits(x = 0, y = 0) +
  coord_cartesian(expand = FALSE, clip = "off")

The argument clip = "off" in any coordinate system, always starting with coord_*, allows to draw outside of the panel area. Call it here to make sure that the tick marks at c(0, 0) are not cut.

5.10 Axes with same scaling

Use coord_equal() with default ratio = 1 to ensure the units are equally scaled on the x-axis and on the y-axis. We can set the aspect ratio of a plot with coord_fixed() or coord_equal(). Both use aspect = 1 (1:1) as a default.

Show the code

ggplot(chic, aes(x = temp, y = temp + rnorm(nrow(chic), sd = 20))) +
  geom_point(color = "sienna") +
  labs(x = "Temperature (°F)", y = "Temperature (°F) + random noise") +
  xlim(c(0, 100)) + ylim(c(0, 150)) +
  coord_fixed()

Warning: Removed 47 rows containing missing values or values outside the scale range
(`geom_point()`).

Ratios higher than one make units on the y axis longer than units on the x-axis, and vice versa:

Show the code

ggplot(chic, aes(x = temp, y = temp + rnorm(nrow(chic), sd = 20))) +
  geom_point(color = "sienna") +
  labs(x = "Temperature (°F)", y = "Temperature (°F) + random noise") +
  xlim(c(0, 100)) + ylim(c(0, 150)) +
  coord_fixed(ratio = 1/5)

Warning: Removed 58 rows containing missing values or values outside the scale range
(`geom_point()`).

5.11 Use a function to alter labels

In case you want to format (eg. adding % sign) without change the data. It’s like lambda in Python!

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "firebrick") +
  labs(x = "Year", y = NULL) +
  scale_y_continuous(label = function(x) {return(paste(x, "Degrees Fahrenheit"))})

6 Titles

6.1 Add a title

We can add a title via ggtitle() function.

Show the code

ggplot(chic, aes(x = date, y = temp)) +
    geom_point(color = "firebrick") +
    labs(x = "Year", y = "Temperature (°F)") +
    ggtitle("Temperatures in Chicago")

Alternatively, we can use labs(), where we can add serveral arguments ~ metadata of the plot (a sub-title, a caption, and a tag):

Show the code

ggplot(chic, aes(x = date, y = temp)) +
    geom_point(color = "firebrick") +
    labs(x = "Year", y = "Temperature (°F)",
        title = "Temperatures in Chicago",
        subtitle = "Seasonal pattern of daily temperatures from 1997 to 2001",
        caption = "Data: NMMAPS",
        tag = "Fig 1")

6.2 Make title bold & add a space at the baseline

We want to, again, modify the properties of a theme element, we use theme() with it elements & conjunctions. These settings not only work for the title, but also for plot.subtitle, plot.caption, plot.tag, legend.title, legend.text, axis.title, and axis.text.

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "firebrick") +
  labs(x = "Year", y = "Temperature (°F)",
       title = "Temperatures in Chicago") +
  theme(plot.title = element_text(face = "bold",
                                  margin = margin(10, 0, 10, 0),
                                  size = 14))

6.3 Adjust the position of titles

We can use the hjust and vjust for horizontal and vertical alighment:

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "firebrick") +
  labs(x = "Year", y = NULL,
       title = "Temperatures in Chicago",
       caption = "Data: NMMAPS") +
  theme(plot.title = element_text(hjust = 1, size = 16, face = "bold.italic"))

But since 2019, we can also use plot.title.position and plot.caption.position. This fit better for the case of long long axis that makes the alignment looks terrible.

The old way:

Show the code

(g <- ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "firebrick") +
  scale_y_continuous(label = function(x) {return(paste(x, "Degrees Fahrenheit"))}) +
  labs(x = "Year", y = NULL,
       title = "Temperatures in Chicago between 1997 and 2001 in Degrees Fahrenheit",
       caption = "Data: NMMAPS") +
  theme(plot.title = element_text(size = 14, face = "bold.italic"),
        plot.caption = element_text(hjust = 0)))

The new one:

Show the code

g + theme(plot.title.position = "plot",
          plot.caption.position = "plot")

6.4 Use a non-traditional font in your title

The fonts you can use are not limited by the ones provided by ggplot2, and the OS/fonts installed as well. We can use showtext for various types of font (TrueType, OpenType, Type 1, web fonts, etc.). The font_acc_google() and font_add() also work well, especially for Google fonts. But note that you must have the fonts installed, then re-load the IDE (Rstudio or VS Code) to use them.

Show the code

library(showtext)

Warning: package 'showtext' was built under R version 4.4.3

Loading required package: sysfonts

Loading required package: showtextdb

Show the code

font_add_google("Playfair Display", ## name of Google font
                "Playfair")  ## name that will be used in R
font_add_google("Bangers", "Bangers")

And then voila we can use them with, again, theme():

Show the code

# From author's code, I've added `showtext_auto()`, then it worked!
# https://stackoverflow.com/questions/56072340/fonts-not-available-in-r-after-importing
showtext_auto()
ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "firebrick") +
  labs(x = "Year", y = "Temperature (°F)",
       title = "Temperatures in Chicago",
       subtitle = "Daily temperatures in °F from 1997 to 2001") +
  theme(plot.title = element_text(family = "Bangers", hjust = .5, size = 25),
        plot.subtitle = element_text(family = "Playfair", hjust = .5, size = 15))

We can also set a font for all elements of our plot globally:

Show the code

font_add_google("Roboto Condensed", "Roboto Condensed")
theme_set(theme_bw(base_size = 12, base_family = "Roboto Condensed"))

6.5 Change spacing in multi-line text

We can use the lineheight to change the spacing between lines, as how we squeezed the lines together below:

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "firebrick") +
  labs(x = "Year", y = "Temperature (°F)") +
  ggtitle("Temperatures in Chicago\nfrom 1997 to 2001") +
  theme(plot.title = element_text(lineheight = .95, size = 16))

7 Legends

We will map the variable season to the aesthetic color. ggplot adds legend by default when we do such thing.

Show the code

ggplot(chic,
       aes(x = date, y = temp, color = season)) +
  geom_point() +
  labs(x = "Year", y = "Temperature (°F)")

7.1 Turn off the legend

Use the theme(legend.position = 'none') to remove the legend:

Show the code

ggplot(chic,
       aes(x = date, y = temp, color = season)) +
  geom_point() +
  labs(x = "Year", y = "Temperature (°F)") +
  theme(legend.position = 'none')

Based on specific case, we can also use the guides(color = 'none') or scale_color_discrete(guide = 'none'). Below we remove the color legend, but retain the shape legend.

Show the code

ggplot(chic,
       aes(x = date, y = temp,
           color = season, shape = season)) +
  geom_point() +
  labs(x = "Year", y = "Temperature (°F)") +
  guides(color = "none")

7.2 Remove legend titles

As learned before, we can use element_blank() to draw nothing.

Show the code

ggplot(chic, aes(x = date, y = temp, color = season)) +
  geom_point() +
  labs(x = "Year", y = "Temperature (°F)") +
  theme(legend.title = element_blank())

Either using scale_color_discrete(name = NULL) or labs(color = NULL) would drive the same result.

7.3 Change legend position

Basically, we can control the position of legend using legend.position in theme. There are top, right (default), bottom, and left:

Show the code

ggplot(chic, aes(x = date, y = temp, color = season)) +
  geom_point() +
  labs(x = "Year", y = "Temperature (°F)") +
  theme(legend.position = "top")

Furthermore, ggplot offers full control as we can specify legend position using “latitude” & “longtitude”. Below we also modified the rectangle’s background color to transparent.

Show the code

ggplot(chic, aes(x = date, y = temp, color = season)) +
  geom_point() +
  labs(x = "Year", y = "Temperature (°F)",
       color = NULL) +
  theme(legend.position = c(.15, .15),
        legend.background = element_rect(fill = "transparent"))

Warning: A numeric `legend.position` argument in `theme()` was deprecated in ggplot2
3.5.0.
ℹ Please use the `legend.position.inside` argument of `theme()` instead.

Update

Update:

A numeric legend.position argument in theme() was deprecated in ggplot2 3.5.0.

ℹ Please use the legend.position.inside argument of theme() instead.

7.4 Change legend direction

You can switch the direction of legend as you like:

Show the code

ggplot(chic, aes(x = date, y = temp, color = season)) +
  geom_point() +
  labs(x = "Year", y = "Temperature (°F)",
       color = NULL) +
  theme(legend.position = c(.15, .15),
        legend.background = element_rect(fill = "transparent")) +
  guides(color = guide_legend(direction = 'horizontal'))

7.5 Change style of the legend title

By modifying the element_text() of legend.title inside theme, we can change the style of legend title.

Show the code

ggplot(chic, aes(x = date, y = temp, color = season)) +
  geom_point() +
  labs(x = "Year", y = "Temperature (°F)") +
  theme(legend.title = element_text(family = "Playfair",
                                    color = "chocolate",
                                    size = 14, face = "bold"))

7.6 Change legend title

The easiest way - labs():

Show the code

ggplot(chic, aes(x = date, y = temp, color = season)) +
  geom_point() +
  labs(x = "Year", y = "Temperature (°F)",
       color = "Seasons\nindicated\nby colors:") +
  theme(legend.title = element_text(family = "Playfair",
                                    color = "chocolate",
                                    size = 14, face = "bold"))

The other ways are: scale_color_discretet(name = "title"), or `guides(color = guide_legend(“title”)).

7.7 Change order of legend keys

Most of the time we want the full control on the order of legend keys. From Credric tutorial we can only change it by modifying the level of variable:

Show the code

chic$season <-
  factor(chic$season,
         levels = c("Winter", "Spring", "Summer", "Autumn"))

ggplot(chic, aes(x = date, y = temp, color = season)) +
  geom_point() +
  labs(x = "Year", y = "Temperature (°F)")

More discussion on the internet, for eg., here.

7.8 Change legend labels

This can be achived by providing information for label in scale_color_discrete():

Show the code

ggplot(chic, aes(x = date, y = temp, color = season)) +
  geom_point() +
  labs(x = "Year", y = "Temperature (°F)") +
  scale_color_discrete(
    name = "Seasons:",
    labels = c("Mar—May", "Jun—Aug", "Sep—Nov", "Dec—Feb")
  ) +
  theme(legend.title = element_text(
    family = "Playfair", color = "chocolate", size = 14, face = 2
  ))

7.9 Change background boxes in the legend

Lies beside the labels are the keys. We can change their background color by modifying the element rectangle of theme legend.key:

Show the code

ggplot(chic, aes(x = date, y = temp, color = season)) +
  geom_point() +
  labs(x = "Year", y = "Temperature (°F)") +
  theme(legend.key = element_rect(fill = "darkgoldenrod1"),
        # fill = NA, fill = "transparent" would remove bg.
        legend.title = element_text(family = "Playfair",
                                    color = "chocolate",
                                    size = 14, face = 2)) +
  scale_color_discrete("Seasons:")

7.10 Change size of legend symbols

The default size is a litle lost in the plot, we can increase it by override the aesthetic using the guides layer again:

Show the code

ggplot(chic, aes(x = date, y = temp, color = season)) +
  geom_point() +
  labs(x = "Year", y = "Temperature (°F)") +
  theme(legend.key = element_rect(fill = NA),
        legend.title = element_text(color = "chocolate",
                                    size = 14, face = 2)) +
  scale_color_discrete("Seasons:") +
  guides(color = guide_legend(override.aes = list(size = 6)))

7.11 Leave a layer of the legend

Duplicate legend happens when we use multiple geom for one data. Like this:

Show the code

ggplot(chic, aes(x = date, y = temp, color = season)) +
  geom_point() +
  labs(x = "Year", y = "Temperature (°F)") +
  geom_rug()

We can turn those redundant ones off by show.legend = FALSE:

Show the code

ggplot(chic, aes(x = date, y = temp, color = season)) +
  geom_point() +
  labs(x = "Year", y = "Temperature (°F)") +
  geom_rug(show.legend = FALSE)

7.12 Manually adding legend items

ggplot2 will not add legend unless you map aesthetic (color, size, etc) to a variable. But there are sometime we want it.

Show the code

ggplot(chic, aes(x = date, y = o3)) +
  geom_line(color = "gray") +
  geom_point(color = "darkorange2") +
  labs(x = "Year", y = "Ozone")

We force legend by providing the color aesthetic mapping to geom:

Show the code

ggplot(chic, aes(x = date, y = o3)) +
  geom_line(aes(color = "line")) +
  geom_point(aes(color = "points")) +
  labs(x = "Year", y = "Ozone") +
  scale_color_discrete("Type:")

Then use the scale_color_manual() to change the color, and override the legend aesthetic using guides() function:

Show the code

ggplot(chic, aes(x = date, y = o3)) +
  geom_line(aes(color = "line")) +
  geom_point(aes(color = "points")) +
  labs(x = "Year", y = "Ozone") +
  scale_color_manual(name = NULL,
                     guide = "legend",
                     values = c("points" = "darkorange2",
                                "line" = "gray")) +
  guides(color = guide_legend(override.aes = list(linetype = c(1, 0),
                                                  shape = c(NA, 16))))

7.13 Use other legend styles

The guide_legend() would work for categorical variable only. It will us guide_colorbar() (or guide_colourbar()) by default for continuous variable.

Show the code

ggplot(chic,
       aes(x = date, y = temp, color = temp)) +
  geom_point() +
  labs(x = "Year", y = "Temperature (°F)", color = "Temperature (°F)")

But guide_legend() still can help you force legend to show discrete colors:

Show the code

ggplot(chic,
       aes(x = date, y = temp, color = temp)) +
  geom_point() +
  labs(x = "Year", y = "Temperature (°F)", color = "Temperature (°F)") +
  guides(color = guide_legend())

We can also use binned scale:

Show the code

ggplot(chic,
       aes(x = date, y = temp, color = temp)) +
  geom_point() +
  labs(x = "Year", y = "Temperature (°F)", color = "Temperature (°F)") +
  guides(color = guide_bins())

or binned scales as discrete colorbars:

Show the code

ggplot(chic,
       aes(x = date, y = temp, color = temp)) +
  geom_point() +
  labs(x = "Year", y = "Temperature (°F)", color = "Temperature (°F)") +
  guides(color = guide_colorsteps())

8 Backgrounds & grid lines

Several ways to change the overall look of your plot as depicted above (see working with themes). But you can also change a particular element of the plotting panel.

8.1 Change the panel background color

By simply specifying the element_rectangle of panel.background inside theme:

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "#1D8565", size = 2) +
  labs(x = "Year", y = "Temperature (°F)") +
  theme(panel.background = element_rect(
    fill = "#64D2AA", color = "#64D2AA", linewidth = 2)
  )

Remember that there is panel.border layer on top of the background (and data), which is also an element_rectangle. So we should use a transparent color here not to hide the data.

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "#1D8565", size = 2) +
  labs(x = "Year", y = "Temperature (°F)") +
  theme(panel.border = element_rect(
    fill = "#64D2AA99", color = "#64D2AA", linewidth = 2)
  )

8.2 Change grid lines

There are 2 type of grid lines and you can change their characteristics using panel.grid.major and panel.grid.minor.

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "firebrick") +
  labs(x = "Year", y = "Temperature (°F)") +
  theme(panel.grid.major = element_line(color = "gray10", linewidth = .5),
        panel.grid.minor = element_line(color = "gray70", linewidth = .25))

We can further make it complex by specifying all 4 different levels:

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "firebrick") +
  labs(x = "Year", y = "Temperature (°F)") +
  theme(panel.grid.major = element_line(linewidth = .5, linetype = "dashed"),
        panel.grid.minor = element_line(linewidth = .25, linetype = "dotted"),
        panel.grid.major.x = element_line(color = "red1"),
        panel.grid.major.y = element_line(color = "blue1"),
        panel.grid.minor.x = element_line(color = "red4"),
        panel.grid.minor.y = element_line(color = "blue4"))

My taste is always remove them:

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "firebrick") +
  labs(x = "Year", y = "Temperature (°F)") +
  theme(panel.grid.minor = element_blank())

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "firebrick") +
  labs(x = "Year", y = "Temperature (°F)") +
  theme(panel.grid = element_blank())

8.3 Change spacing of grid lines

We can also change the spacing behaviour:

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "firebrick") +
  labs(x = "Year", y = "Temperature (°F)") +
  scale_y_continuous(breaks = seq(0, 100, 10),
                     minor_breaks = seq(0, 100, 2.5))

8.4 Change the plot background color

Similar to the plotting panel, we can change the whole plot background color:

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "firebrick") +
  labs(x = "Year", y = "Temperature (°F)") +
  theme(plot.background = element_rect(fill = "gray60",
                                       color = "gray30", linewidth = 2))

By specifying the same color for both plot and panel, you can achive a unified plot color.

9 Margins

Sometime we need more space between the plot border to the plot panel/area - so called the margin. We can use plot.margin in this circumstance:

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "firebrick") +
  labs(x = "Year", y = "Temperature (°F)") +
  theme(plot.background = element_rect(fill = "gray60"),
        plot.margin = margin(t = 1, r = 3, b = 1, l = 8, unit = "cm"))

Show the code

        # can also use plot.margin = unit(c(1, 3, 1, 8), "cm"))

10 Multi-panel plots

ggplot2 offers 2 handy functions for multiple-small visualization: facet_grid() and facet_wrap().

10.1 Create a small multiples based on two variables

In case of 2 variables, facet_grid does the job.

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "orangered", alpha = .3) +
  theme(axis.text.x = element_text(angle = 45, vjust = 1, hjust = 1)) +
  labs(x = "Year", y = "Temperature (°F)") +
  facet_grid(year ~ season)

Show the code

  # remember year ~ season != season ~ year

10.2 Create a small mutilples based on one variables

facet_wrap create a facet from single a variable, the appearance of subplots is controlled by ncol and nrow.

Show the code

g <-
  ggplot(chic, aes(x = date, y = temp)) +
    geom_point(color = "chartreuse4", alpha = .3) +
    labs(x = "Year", y = "Temperature (°F)") +
    theme(axis.text.x = element_text(angle = 45, vjust = 1, hjust = 1))

g + facet_wrap(~ year)

1 rows matrix:

Show the code

g + facet_wrap(~ year, nrow = 1)

or whatever we like”

Show the code

g + facet_wrap(~ year, ncol = 3) + theme(axis.title.x = element_text(hjust = .15))

10.3 Allow axes to roam free

Sometime you want the x and y axis to roam free according to data. This is not a good idea as it makes plots are quite un-comparable. But there it is:

Show the code

g + facet_wrap(~ year, nrow = 2, scales = "free")

10.4 Use `facet_wrap` with two variables

The function facet_wrap is more versatile:

Show the code

g + facet_wrap(year ~ season, nrow = 4, scales = "free_x")

It gives you more control of the plot design. In contrast, facet_grid while also have roam free ability, but just column-wise or row-wise:

Show the code

g + facet_grid(year ~ season, scales = "free_x")

10.5 Modify the strip text

Strip texts and strip text boxes are the title of each subplot, you can modify them using theme:

Show the code

g + facet_wrap(~ year, nrow = 1, scales = "free_x") +
  theme(strip.text = element_text(face = "bold", color = "chartreuse4",
                                  hjust = 0, size = 20),
        strip.background = element_rect(fill = "chartreuse3", linetype = "dotted"))

These 2 functions are adapted by Cedric from this answer of Claus Wilke, author of ggtext, allowing to hightlight specific labels:

Show the code

library(ggtext)

Warning: package 'ggtext' was built under R version 4.4.3

Show the code

library(purrr) ## for %||%

element_textbox_highlight <- function(..., hi.labels = NULL, hi.fill = NULL,
                                      hi.col = NULL, hi.box.col = NULL, hi.family = NULL) {
  structure(
    c(element_textbox(...),
      list(hi.labels = hi.labels, hi.fill = hi.fill, hi.col = hi.col, hi.box.col = hi.box.col, hi.family = hi.family)
    ),
    class = c("element_textbox_highlight", "element_textbox", "element_text", "element")
  )
}

element_grob.element_textbox_highlight <- function(element, label = "", ...) {
  if (label %in% element$hi.labels) {
    element$fill <- element$hi.fill %||% element$fill
    element$colour <- element$hi.col %||% element$colour
    element$box.colour <- element$hi.box.col %||% element$box.colour
    element$family <- element$hi.family %||% element$family
  }
  NextMethod()
}

Use it for all strip texts:

Show the code

g + facet_wrap(year ~ season, nrow = 4, scales = "free_x") +
  theme(
    strip.background = element_blank(),
    strip.text = element_textbox_highlight(
      family = "Playfair", size = 12, face = "bold",
      fill = "white", box.color = "chartreuse4", color = "chartreuse4",
      halign = .5, linetype = 1, r = unit(5, "pt"), width = unit(1, "npc"),
      padding = margin(5, 0, 3, 0), margin = margin(0, 1, 3, 1),
      hi.labels = c("1997", "1998", "1999", "2000"),
      hi.fill = "chartreuse4", hi.box.col = "black", hi.col = "white"
    )
  )

Or hightlight one among others:

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(aes(color = season == "Summer"), alpha = .3) +
  labs(x = "Year", y = "Temperature (°F)") +
  facet_wrap(~ season, nrow = 1) +
  scale_color_manual(values = c("gray40", "firebrick"), guide = "none") +
  theme(
    axis.text.x = element_text(angle = 45, vjust = 1, hjust = 1),
    strip.background = element_blank(),
    strip.text = element_textbox_highlight(
      size = 12, face = "bold",
      fill = "white", box.color = "white", color = "gray40",
      halign = .5, linetype = 1, r = unit(0, "pt"), width = unit(1, "npc"),
      padding = margin(2, 0, 1, 0), margin = margin(0, 1, 3, 1),
      hi.labels = "Summer", hi.family = "Bangers",
      hi.fill = "firebrick", hi.box.col = "firebrick", hi.col = "white"
    )
  )

10.6 Create a panel of different plots

Extension is all you need, and in this case is patchwork by Thomas Lin Pedersen:

Show the code

p1 <- ggplot(chic, aes(x = date, y = temp,
                       color = season)) +
        geom_point() +
        geom_rug() +
        labs(x = "Year", y = "Temperature (°F)")

p2 <- ggplot(chic, aes(x = date, y = o3)) +
        geom_line(color = "gray") +
        geom_point(color = "darkorange2") +
        labs(x = "Year", y = "Ozone")

library(patchwork)

Warning: package 'patchwork' was built under R version 4.4.3

Show the code

p1 + p2

Make them vertically aligned by “dividing” them:

Show the code

p1 / p2

And more fun :)

Show the code

(g + p2) / p1

An alternative is cowplot by Claus Wilke:

Show the code

library(cowplot)

Warning: package 'cowplot' was built under R version 4.4.3


Attaching package: 'cowplot'

The following object is masked from 'package:patchwork':

    align_plots

Show the code

plot_grid(plot_grid(g, p1), p2, ncol = 1)

Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database

Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database

Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database

Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Roboto Condensed' not found in PostScript font database

Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Roboto Condensed' not found in PostScript font database

And the gridExtra as well.

Show the code

library(gridExtra)

Warning: package 'gridExtra' was built under R version 4.4.3

Show the code

grid.arrange(g, p1, p2,
             layout_matrix = rbind(c(1, 2), c(3, 3)))

More complex layouts can be defined using patchwork:

Show the code

layout <- "
AABBBB#
AACCDDE
##CCDD#
##CC###
"

p2 + p1 + p1 + g + p2 + plot_layout(design = layout)

11. Colors

In ggplot2, both color and fill can be:

specified as single color, or
assigned to variables.

Those variables that are inside the aesthetic have mapping encoded, and those are outside are unrelated properties.

Show the code

ggplot(chic, aes(year)) +
  geom_bar(aes(fill = season), color = "grey", linewidth = 2) +
  labs(x = "Year", y = "Observations", fill = "Season:")

11.1 Specify single colors

We can specify single color for a geom:

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "steelblue", size = 2) +
  labs(x = "Year", y = "Temperature (°F)")

And if provide both, color (outline) and fill (fill):

Show the code

ggplot(chic, aes(x = date, y = temp)) +
  geom_point(shape = 21, size = 2, stroke = 1,
             color = "#3cc08f", fill = "#c08f3c") +
  labs(x = "Year", y = "Temperature (°F)")

Refer then PDF of R color. You can also use hex, RGB or RGBA (via rgb(red, green, blue, alpha)).

11.2 Asign colors to variables

In ggplot2, colors that are assigned to a variables are modified via scale_color_* or scale_fill_*. You should understand what kind of variable you are dealing with (categorical or continuous) to effectively encode those (sequential, deverging, qualitative, etc).

11.3 Qualitative variables

Qualitative can be nominal, ordinal, or binary. By defalt the categorical color paletted looks like this:

Show the code

(ga <- ggplot(chic, aes(x = date, y = temp, color = season)) +
  geom_point() +
  labs(x = "Year", y = "Temperature (°F)", color = NULL))

11.3.1 Manually select qualitative colors

You can manually assign a set of colors to each category of qualitative colors (number of color has to match number of category) via scale_*_manual() (color, colour, or fill):

Show the code

ga + scale_color_manual(values = c("dodgerblue4",
                                   "darkolivegreen4",
                                   "darkorchid3",
                                   "goldenrod1"))

11.3.2 Use built-in qualitative color palettes

There are scale_*_brewer() implemented the ColorBrewer palettes already:

Show the code

ga + scale_color_brewer(palette = "Set1")

11.3.3 Use qualitative colors palettes from extension packages

There are several packages are created for this, and we can check it at this collection of Emil Hvitfeldt. For eg, paletteer or ggthemes:

Show the code

library(ggthemes)

Warning: package 'ggthemes' was built under R version 4.4.3


Attaching package: 'ggthemes'

The following object is masked from 'package:cowplot':

    theme_map

Show the code

ga + scale_color_tableau()

ggsci provide the scientific journal and sci-fi themed color palettes:

Show the code

library(ggsci)

Warning: package 'ggsci' was built under R version 4.4.3

Show the code

g1 <- ga + scale_color_aaas()
g2 <- ga + scale_color_npg()

library(patchwork)
(g1 + g2) * theme(legend.position = "top")

11.4 Quantitiave variables

This is default function for sequential color scheme for continuous variables:

Show the code

gb <- ggplot(chic, aes(x = date, y = temp, color = temp)) +
  geom_point() +
  labs(x = "Year", y = "Temperature (°F)", color = "Temperature (°F):")

gb + scale_color_continuous()

The scale_*_gradient() would do the same:

Show the code

gb + scale_color_gradient()

And the scale_*_gradient2() would do the divergent color scheme:

Show the code

mid <- mean(chic$temp)  ## midpoint

gb + scale_color_gradient2(midpoint = mid)

11.4.1 Manually set a sequential color scheme

By providing information to the argument of scale_*_gradient():

Show the code

gb + scale_color_gradient(low = "darkkhaki",
                          high = "darkgreen")

How about scale_*_gradient2():

Show the code

gb + scale_color_gradient2(midpoint = mid, low = "#dd8a0b",
                           mid = "grey92", high = "#32a676")

11.4.2 The beautiful Viridis color palette

The viridis color palettes will make your chart:

looks more pretty;
well prints in grey scale;
easier to read by colorblindess. (refer dichromat package)

and it is built in function in ggplot2:

Show the code

p1 <- gb + scale_color_viridis_c() + ggtitle("'viridis' (default)")
p2 <- gb + scale_color_viridis_c(option = "inferno") + ggtitle("'inferno'")
p3 <- gb + scale_color_viridis_c(option = "plasma") + ggtitle("'plasma'")
p4 <- gb + scale_color_viridis_c(option = "cividis") + ggtitle("'cividis'")

library(patchwork)
(p1 + p2 + p3 + p4) * theme(legend.position = "bottom")

as well as discrete colors:

Show the code

ga + scale_color_viridis_d(guide = "none")

11.4.3 Extension packages

There are several packages are created for this, and we can check it at this collection of Emil Hvitfeldt. For example, the rcartocolors ports the CARTOcolors to ggplot2:

Show the code

library(rcartocolor)

Warning: package 'rcartocolor' was built under R version 4.4.3

Show the code

g1 <- gb + scale_color_carto_c(palette = "BurgYl")
g2 <- gb + scale_color_carto_c(palette = "Earth")

(g1 + g2) * theme(legend.position = "bottom")

The second one is scico, provides the access to scientific color maps developed by Fabio Crameri.

Show the code

library(scico)

Warning: package 'scico' was built under R version 4.4.3

Show the code

g1 <- gb + scale_color_scico(palette = "berlin")
g2 <- gb + scale_color_scico(palette = "hawaii", direction = -1)

(g1 + g2) * theme(legend.position = "bottom")

11.5 Modify color palettes afterwards

Why should we do that? Current we know that the ggplot2 can only hanle one color and one fill scale, this funtionality, which the package had already provide after_scale(), can help us flag an evaluation mapping between these two after data had been scaled.

Below example is an usage of clr_negate() from the package primastic:

Show the code

library(prismatic)

Warning: package 'prismatic' was built under R version 4.4.3

Show the code

ggplot(chic, aes(date, temp, color = temp)) +
  geom_point(size = 5) +
  geom_point(aes(color = temp,
                 color = after_scale(clr_negate(color))),
             size = 2) +
  scale_color_scico(palette = "hawaii", guide = "none") +
  labs(x = "Year", y = "Temperature (°F)")

Warning: Duplicated aesthetics after name standardisation: colour

There are also lot of fun work with the package: clr_negate(), clr_lighten(), clr_darken() and clr_desaturate().

Show the code

library(prismatic)

ggplot(chic, aes(date, temp)) +
  geom_boxplot(
    aes(color = season,
        fill = after_scale(clr_desaturate(clr_lighten(color, .6), .6))),
    linewidth = 1
  ) +
  scale_color_brewer(palette = "Dark2", guide = "none") +
  labs(x = "Year", y = "Temperature (°F)")

Read more on the control aesthetic evaluation.

12. Themes

12.1 Change the overall plotting themes

By default ggplot2 provides eight themes, but there are several packages provide additional themes. For example ggthemes. We can simply have The Economist plotting style with theme_economist() và scale_color_economist():

Show the code

library(ggthemes)

ggplot(chic, aes(x = date, y = temp, color = season)) +
  geom_point() +
  labs(x = "Year", y = "Temperature (°F)") +
  ggtitle("Ups and Downs of Chicago's Daily Temperatures") +
  theme_economist() +
  scale_color_economist(name = NULL)

Another style that follow the famous author Edward Tufte of the book “The Visual Display of Quantitative Information”:

Show the code

library(dplyr)


Attaching package: 'dplyr'

The following object is masked from 'package:gridExtra':

    combine

The following objects are masked from 'package:stats':

    filter, lag

The following objects are masked from 'package:base':

    intersect, setdiff, setequal, union

Show the code

chic_2000 <- filter(chic, year == 2000)

ggplot(chic_2000, aes(x = temp, y = o3)) +
  geom_point() +
  labs(x = "Temperature (°F)", y = "Ozone") +
  ggtitle("Temperature and Ozone Levels During the Year 2000 in Chicago") +
  theme_tufte()

Another packages, hrbrthemes by Bob Rudis:

Show the code

library(hrbrthemes)

Warning: package 'hrbrthemes' was built under R version 4.4.3

Show the code

ggplot(chic, aes(x = temp, y = o3)) +
  geom_point(aes(color = dewpoint), show.legend = FALSE) +
  labs(x = "Temperature (°F)", y = "Ozone") +
  ggtitle("Temperature and Ozone Levels in Chicago")

12.2 Change the font of all text elelments

Incredibly easy, using base_family:

Show the code

g <- ggplot(chic, aes(x = date, y = temp)) +
  geom_point(color = "firebrick") +
  labs(x = "Year", y = "Temperature (°F)",
       title = "Temperatures in Chicago")

g + theme_bw(base_family = "Playfair")

12.3 Change the size of all text elements

theme_bw also comes with several base_* argument, here for the text size:

Show the code

g + theme_bw(base_size = 30, base_family = "Roboto Condensed")

12.4 Change the size of all lines and rect elements

Show the code

g + theme_bw(base_line_size = 1, base_rect_size = 1)

12.5 Create your own theme

You can control for an entire session using theme_set as in theme_set(theme_bw()), the default is called theme_gray:

You can view the code inside a theme for modification of your own:

Show the code

theme_gray

function (base_size = 11, base_family = "", base_line_size = base_size/22, 
    base_rect_size = base_size/22) 
{
    half_line <- base_size/2
    t <- theme(line = element_line(colour = "black", linewidth = base_line_size, 
        linetype = 1, lineend = "butt"), rect = element_rect(fill = "white", 
        colour = "black", linewidth = base_rect_size, linetype = 1), 
        text = element_text(family = base_family, face = "plain", 
            colour = "black", size = base_size, lineheight = 0.9, 
            hjust = 0.5, vjust = 0.5, angle = 0, margin = margin(), 
            debug = FALSE), axis.line = element_blank(), axis.line.x = NULL, 
        axis.line.y = NULL, axis.text = element_text(size = rel(0.8), 
            colour = "grey30"), axis.text.x = element_text(margin = margin(t = 0.8 * 
            half_line/2), vjust = 1), axis.text.x.top = element_text(margin = margin(b = 0.8 * 
            half_line/2), vjust = 0), axis.text.y = element_text(margin = margin(r = 0.8 * 
            half_line/2), hjust = 1), axis.text.y.right = element_text(margin = margin(l = 0.8 * 
            half_line/2), hjust = 0), axis.text.r = element_text(margin = margin(l = 0.8 * 
            half_line/2, r = 0.8 * half_line/2), hjust = 0.5), 
        axis.ticks = element_line(colour = "grey20"), axis.ticks.length = unit(half_line/2, 
            "pt"), axis.ticks.length.x = NULL, axis.ticks.length.x.top = NULL, 
        axis.ticks.length.x.bottom = NULL, axis.ticks.length.y = NULL, 
        axis.ticks.length.y.left = NULL, axis.ticks.length.y.right = NULL, 
        axis.minor.ticks.length = rel(0.75), axis.title.x = element_text(margin = margin(t = half_line/2), 
            vjust = 1), axis.title.x.top = element_text(margin = margin(b = half_line/2), 
            vjust = 0), axis.title.y = element_text(angle = 90, 
            margin = margin(r = half_line/2), vjust = 1), axis.title.y.right = element_text(angle = -90, 
            margin = margin(l = half_line/2), vjust = 1), legend.background = element_rect(colour = NA), 
        legend.spacing = unit(2 * half_line, "pt"), legend.spacing.x = NULL, 
        legend.spacing.y = NULL, legend.margin = margin(half_line, 
            half_line, half_line, half_line), legend.key = NULL, 
        legend.key.size = unit(1.2, "lines"), legend.key.height = NULL, 
        legend.key.width = NULL, legend.key.spacing = unit(half_line, 
            "pt"), legend.text = element_text(size = rel(0.8)), 
        legend.title = element_text(hjust = 0), legend.ticks.length = rel(0.2), 
        legend.position = "right", legend.direction = NULL, legend.justification = "center", 
        legend.box = NULL, legend.box.margin = margin(0, 0, 0, 
            0, "cm"), legend.box.background = element_blank(), 
        legend.box.spacing = unit(2 * half_line, "pt"), panel.background = element_rect(fill = "grey92", 
            colour = NA), panel.border = element_blank(), panel.grid = element_line(colour = "white"), 
        panel.grid.minor = element_line(linewidth = rel(0.5)), 
        panel.spacing = unit(half_line, "pt"), panel.spacing.x = NULL, 
        panel.spacing.y = NULL, panel.ontop = FALSE, strip.background = element_rect(fill = "grey85", 
            colour = NA), strip.clip = "inherit", strip.text = element_text(colour = "grey10", 
            size = rel(0.8), margin = margin(0.8 * half_line, 
                0.8 * half_line, 0.8 * half_line, 0.8 * half_line)), 
        strip.text.x = NULL, strip.text.y = element_text(angle = -90), 
        strip.text.y.left = element_text(angle = 90), strip.placement = "inside", 
        strip.placement.x = NULL, strip.placement.y = NULL, strip.switch.pad.grid = unit(half_line/2, 
            "pt"), strip.switch.pad.wrap = unit(half_line/2, 
            "pt"), plot.background = element_rect(colour = "white"), 
        plot.title = element_text(size = rel(1.2), hjust = 0, 
            vjust = 1, margin = margin(b = half_line)), plot.title.position = "panel", 
        plot.subtitle = element_text(hjust = 0, vjust = 1, margin = margin(b = half_line)), 
        plot.caption = element_text(size = rel(0.8), hjust = 1, 
            vjust = 1, margin = margin(t = half_line)), plot.caption.position = "panel", 
        plot.tag = element_text(size = rel(1.2), hjust = 0.5, 
            vjust = 0.5), plot.tag.position = "topleft", plot.margin = margin(half_line, 
            half_line, half_line, half_line), complete = TRUE)
    ggplot_global$theme_all_null %+replace% t
}
<bytecode: 0x0000011a530605b0>
<environment: namespace:ggplot2>

We can literally modify everything in the theme:

Show the code

theme_custom <- function (base_size = 12, base_family = "Roboto Condensed") {
  half_line <- base_size/2
  theme(
    line = element_line(color = "black", linewidth = .5,
                        linetype = 1, lineend = "butt"),
    rect = element_rect(fill = "white", color = "black",
                        linewidth = .5, linetype = 1),
    text = element_text(family = base_family, face = "plain",
                        color = "black", size = base_size,
                        lineheight = .9, hjust = .5, vjust = .5,
                        angle = 0, margin = margin(), debug = FALSE),
    axis.line = element_blank(),
    axis.line.x = NULL,
    axis.line.y = NULL,
    axis.text = element_text(size = base_size * 1.1, color = "gray30"),
    axis.text.x = element_text(margin = margin(t = .8 * half_line/2),
                               vjust = 1),
    axis.text.x.top = element_text(margin = margin(b = .8 * half_line/2),
                                   vjust = 0),
    axis.text.y = element_text(margin = margin(r = .8 * half_line/2),
                               hjust = 1),
    axis.text.y.right = element_text(margin = margin(l = .8 * half_line/2),
                                     hjust = 0),
    axis.ticks = element_line(color = "gray30", linewidth = .7),
    axis.ticks.length = unit(half_line / 1.5, "pt"),
    axis.ticks.length.x = NULL,
    axis.ticks.length.x.top = NULL,
    axis.ticks.length.x.bottom = NULL,
    axis.ticks.length.y = NULL,
    axis.ticks.length.y.left = NULL,
    axis.ticks.length.y.right = NULL,
    axis.title.x = element_text(margin = margin(t = half_line),
                                vjust = 1, size = base_size * 1.3,
                                face = "bold"),
    axis.title.x.top = element_text(margin = margin(b = half_line),
                                    vjust = 0),
    axis.title.y = element_text(angle = 90, vjust = 1,
                                margin = margin(r = half_line),
                                size = base_size * 1.3, face = "bold"),
    axis.title.y.right = element_text(angle = -90, vjust = 0,
                                      margin = margin(l = half_line)),
    legend.background = element_rect(color = NA),
    legend.spacing = unit(.4, "cm"),
    legend.spacing.x = NULL,
    legend.spacing.y = NULL,
    legend.margin = margin(.2, .2, .2, .2, "cm"),
    legend.key = element_rect(fill = "gray95", color = "white"),
    legend.key.size = unit(1.2, "lines"),
    legend.key.height = NULL,
    legend.key.width = NULL,
    legend.text = element_text(size = rel(.8)),
    legend.text.align = NULL,
    legend.title = element_text(hjust = 0),
    legend.title.align = NULL,
    legend.position = "right",
    legend.direction = NULL,
    legend.justification = "center",
    legend.box = NULL,
    legend.box.margin = margin(0, 0, 0, 0, "cm"),
    legend.box.background = element_blank(),
    legend.box.spacing = unit(.4, "cm"),
    panel.background = element_rect(fill = "white", color = NA),
    panel.border = element_rect(color = "gray30",
                                fill = NA, linewidth = .7),
    panel.grid.major = element_line(color = "gray90", linewidth = 1),
    panel.grid.minor = element_line(color = "gray90", linewidth = .5,
                                    linetype = "dashed"),
    panel.spacing = unit(base_size, "pt"),
    panel.spacing.x = NULL,
    panel.spacing.y = NULL,
    panel.ontop = FALSE,
    strip.background = element_rect(fill = "white", color = "gray30"),
    strip.text = element_text(color = "black", size = base_size),
    strip.text.x = element_text(margin = margin(t = half_line,
                                                b = half_line)),
    strip.text.y = element_text(angle = -90,
                                margin = margin(l = half_line,
                                                r = half_line)),
    strip.text.y.left = element_text(angle = 90),
    strip.placement = "inside",
    strip.placement.x = NULL,
    strip.placement.y = NULL,
    strip.switch.pad.grid = unit(0.1, "cm"),
    strip.switch.pad.wrap = unit(0.1, "cm"),
    plot.background = element_rect(color = NA),
    plot.title = element_text(size = base_size * 1.8, hjust = .5,
                              vjust = 1, face = "bold",
                              margin = margin(b = half_line * 1.2)),
    plot.title.position = "panel",
    plot.subtitle = element_text(size = base_size * 1.3,
                                 hjust = .5, vjust = 1,
                                 margin = margin(b = half_line * .9)),
    plot.caption = element_text(size = rel(0.9), hjust = 1, vjust = 1,
                                margin = margin(t = half_line * .9)),
    plot.caption.position = "panel",
    plot.tag = element_text(size = rel(1.2), hjust = .5, vjust = .5),
    plot.tag.position = "topleft",
    plot.margin = margin(rep(base_size, 4)),
    complete = TRUE
  )
}

Then use it:

Show the code

theme_set(theme_custom())

ggplot(chic, aes(x = date, y = temp, color = season)) +
  geom_point() + labs(x = "Year", y = "Temperature (°F)") + guides(color = "none")

12.6 Update the current theme

A ggplot is extendable, so is theme - using theme_update:

Show the code

theme_custom <- theme_update(panel.background = element_rect(fill = "gray60"))

ggplot(chic, aes(x = date, y = temp, color = season)) +
  geom_point() + labs(x = "Year", y = "Temperature (°F)") + guides(color = "none")

13. Lines

Show the code

theme_custom <- theme_update(
  panel.background = element_rect(fill = "white"),
  panel.grid.major = element_line(linewidth = .5),
  panel.grid.minor = element_blank()
)

13.1 Add horizontal or vertical lines to a plot

We might want to plot a horizontal or vertical line across the plot to highlight a threshold, or an event. This can be done using geom_vline() or geom_hline():

Show the code

ggplot(chic, aes(x = date, y = temp, color = o3)) +
  geom_point() +
  geom_hline(yintercept = c(0, 73)) +
  labs(x = "Year", y = "Temperature (°F)")

More customization on the lines:

Show the code

g <- ggplot(chic, aes(x = temp, y = dewpoint)) +
  geom_point(color = "dodgerblue", alpha = .5) +
  labs(x = "Temperature (°F)", y = "Dewpoint")

g +
  geom_vline(aes(xintercept = median(temp)), linewidth = 1.5,
             color = "firebrick", linetype = "dashed") +
  geom_hline(aes(yintercept = median(dewpoint)), linewidth = 1.5,
             color = "firebrick", linetype = "dashed")

A sloping line also can be added using geom_abline() (later we will learn how to add a linear fit with stat_smooth(method = "lm")):

Show the code

reg <- lm(dewpoint ~ temp, data = chic)

g +
  geom_abline(intercept = coefficients(reg)[1],
              slope = coefficients(reg)[2],
              color = "darkorange2",
              linewidth = 1.5) +
  labs(title = paste0("y = ", round(coefficients(reg)[2], 2),
                      " * x + ", round(coefficients(reg)[1], 2)))

13.2 Add a line within a plot

One might need to limited the length of line, just for a certain range. This is when geom_linerange() comes to help:

Show the code

g +
  ## vertical line
  geom_linerange(aes(x = 50, ymin = 20, ymax = 55),
                 color = "steelblue", linewidth = 2) +
  ## horizontal line
  geom_linerange(aes(xmin = -Inf, xmax = 25, y = 0),
                 color = "red", linewidth = 1)

Or you can use annotate(geom = "segment") to add a sloping line:

Show the code

g +
  annotate(geom = "segment",
           x = 50, xend = 75,
                   y = 20, yend = 45,
               color = "purple", linewidth = 2)

13.3 Add curved lines and arrows to a plot

If we set geom = "curves", we have curved lines:

Show the code

g +
  annotate(geom = "curve",x = 0, y = 60, xend = 75, yend = 0,
             color = "tan", linewidth = 2) +
  annotate(geom = "curve",
           x = 0, y = 60, xend = 75, yend = 0,
             curvature = -0.7, angle = 45,
             color = "darkgoldenrod1", linewidth = 1) +
  annotate(geom = "curve", x = 0, y = 60, xend = 75, yend = 0,
             curvature = 0, linewidth = 1.5)

If we want to add arrows:

Show the code

g +
  annotate(geom = "curve", x = 0, y = 60, xend = 75, yend = 0,
             color = "tan", linewidth = 2,
             arrow = arrow(length = unit(0.07, "npc"))) +
  annotate(geom = "curve", x = 5, y = 55, xend = 70, yend = 5,
             curvature = -0.7, angle = 45,
             color = "darkgoldenrod1", linewidth = 1,
             arrow = arrow(length = unit(0.03, "npc"),
                           type = "closed",
                           ends = "both"))

14. Text

14.1 Add labels to your data

Show the code

set.seed(2020)

## just label 1% dataset, equally for each season
sample <- chic |>
  dplyr::group_by(season) |>
  dplyr::sample_frac(0.01)

## code without pipes:
## sample <- sample_frac(group_by(chic, season), .01)

ggplot(sample, aes(x = date, y = temp, color = season)) +
  geom_point(data = chic) +
  geom_label(aes(label = season), hjust = .5, vjust = -.5) +
  ## can use `geom_text()` if we dont want boxes around lables
  labs(x = "Year", y = "Temperature (°F)") +
  xlim(as.Date(c('1997-01-01', '2000-12-31'))) +
  ylim(c(0, 90)) +
  theme(legend.position = "none")

Warning: Removed 3 rows containing missing values or values outside the scale range
(`geom_point()`).

Text are overlapping! the the package ggrepel comes to solve, just simply replace geom_text() by geom_text_repel(), and geom_label() by geom_label_repel():

Show the code

library(ggrepel)

Warning: package 'ggrepel' was built under R version 4.4.3

Show the code

ggplot(sample, aes(x = date, y = temp, color = season)) +
  geom_point(data = chic) +
  geom_label_repel(aes(label = season), fontface = "bold") +
  labs(x = "Year", y = "Temperature (°F)") +
  theme(legend.position = "none")

It may look nicer when we map season to fill instead of color:

Show the code

ggplot(sample, aes(x = date, y = temp)) +
  geom_point(data = chic, size = .5) +
  geom_point(aes(color = season), size = 1.5) +
  geom_label_repel(aes(label = season, fill = season),
                   color = "white", fontface = "bold",
                   segment.color = "grey30") +
  labs(x = "Year", y = "Temperature (°F)") +
  theme(legend.position = "none")

14.2 Add text annotations

Several ways: annotate(geom = "text"), annotate(geom = "label"), geom_text() or geom_label():

Show the code

g <-
  ggplot(chic, aes(x = temp, y = dewpoint)) +
  geom_point(alpha = .5) +
  labs(x = "Temperature (°F)", y = "Dewpoint")

g +
  annotate(geom = "text", x = 25, y = 60, fontface = "bold",
                label = "This is a useful annotation")

The problem is ggplot had drawn one text for one data point ~ 1462 labels and you only see one. We can solve this by:

Show the code

g +
  geom_text(aes(x = 25, y = 60,
                label = "This is a useful annotation"),
            stat = "unique")

Warning in geom_text(aes(x = 25, y = 60, label = "This is a useful annotation"), : All aesthetics have length 1, but the data has 1461 rows.
ℹ Please consider using `annotate()` or provide this layer with data containing
  a single row.

Change the properties of displayed text:

Show the code

g +
  geom_text(aes(x = 25, y = 60,
                label = "This is a useful annotation"),
            stat = "unique", family = "Bangers",
            size = 7, color = "darkcyan")

Warning in geom_text(aes(x = 25, y = 60, label = "This is a useful annotation"), : All aesthetics have length 1, but the data has 1461 rows.
ℹ Please consider using `annotate()` or provide this layer with data containing
  a single row.

You might run into trouble when annotating with facets:

Show the code

ann <- data.frame(
  o3 = 30,
  temp = 20,
  season = factor("Summer", levels = levels(chic$season)),
  label = "Here is enough space\nfor some annotations."
)

g <-
  ggplot(chic, aes(x = o3, y = temp)) +
  geom_point() +
  labs(x = "Ozone", y = "Temperature (°F)")

g +
  geom_text(data = ann, aes(label = label),
            size = 7, fontface = "bold",
            family = "Roboto Condensed") +
  facet_wrap(~season)

Freescaling may cut your text:

Show the code

g +
  geom_text(aes(x = 23, y = 97,
                label = "This is not a useful annotation"),
            size = 5, fontface = "bold") +
  scale_y_continuous(limits = c(NA, 100)) +
  facet_wrap(~season, scales = "free_x")

Warning in geom_text(aes(x = 23, y = 97, label = "This is not a useful annotation"), : All aesthetics have length 1, but the data has 1461 rows.
ℹ Please consider using `annotate()` or provide this layer with data containing
  a single row.

One workaround might be calculating the midpoint beforehand:

Show the code

ann <-
  chic |>
  dplyr::group_by(season) |>
  dplyr::summarize(
    o3 = min(o3, na.rm = TRUE) +
          (max(o3, na.rm = TRUE) - min(o3, na.rm = TRUE)) / 2
)

ann

# A tibble: 4 × 2
  season    o3
  <fct>  <dbl>
1 Winter  21.5
2 Spring  31.0
3 Summer  29.2
4 Autumn  23.3

Then use it:

Show the code

g +
  geom_text(data = ann,
            aes(x = o3, y = 97,
                label = "This is a useful annotation"),
            size = 5, fontface = "bold") +
  scale_y_continuous(limits = c(NA, 100)) +
  facet_wrap(~season, scales = "free_x")

And there are also advanced solotions:

Show the code

library(grid)
my_grob <- grobTree(textGrob("This text stays in place!",
                             x = .1, y = .9, hjust = 0,
                             gp = gpar(col = "black",
                                       fontsize = 15,
                                       fontface = "bold")))

g +
  annotation_custom(my_grob) +
  facet_wrap(~season, scales = "free_x") +
  scale_y_continuous(limits = c(NA, 100))

14.3 Use markdown and HTML rendering for annotations

ggtext provide syntax for markdown:

Show the code

library(ggtext)

lab_md <- "This plot shows **temperature** in *°F* versus **ozone level** in *ppm*"

g +
  geom_richtext(aes(x = 35, y = 3, label = lab_md),
                stat = "unique")

Warning in geom_richtext(aes(x = 35, y = 3, label = lab_md), stat = "unique"): All aesthetics have length 1, but the data has 1461 rows.
ℹ Please consider using `annotate()` or provide this layer with data containing
  a single row.

and also HTML:

Show the code

lab_html <- "&#9733; This plot shows <b style='color:red;'>temperature</b> in <i>°F</i> versus <b style='color:blue;'>ozone level</b>in <i>ppm</i> &#9733;"

g +
  geom_richtext(aes(x = 33, y = 3, label = lab_html),
                stat = "unique")

Warning in geom_richtext(aes(x = 33, y = 3, label = lab_html), stat = "unique"): All aesthetics have length 1, but the data has 1461 rows.
ℹ Please consider using `annotate()` or provide this layer with data containing
  a single row.

They allow lots of customizations:

Show the code

g +
  geom_richtext(aes(x = 10, y = 25, label = lab_md),
                stat = "unique", angle = 30,
                color = "white", fill = "steelblue",
                label.color = NA, hjust = 0, vjust = 0,
                family = "Playfair Display")

Warning in geom_richtext(aes(x = 10, y = 25, label = lab_md), stat = "unique", : All aesthetics have length 1, but the data has 1461 rows.
ℹ Please consider using `annotate()` or provide this layer with data containing
  a single row.

Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead

Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead

Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead

Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead

Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead

Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_stringMetric, as.graphicsAnnot(x$label)): font family
'Playfair Display' not found, will use 'sans' instead

Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call(C_textBounds, as.graphicsAnnot(x$label), x$x, x$y, : font
family 'Playfair Display' not found, will use 'sans' instead

Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead
Warning in grid.Call.graphics(C_text, as.graphicsAnnot(x$label), x$x, x$y, :
font family 'Playfair Display' not found, will use 'sans' instead

The other from ggtext is geom_textbox():

Show the code

lab_long <- "**Lorem ipsum dolor**<br><i style='font-size:8pt;color:red;'>Lorem ipsum dolor sit amet, consectetur adipiscing elit, sed do eiusmod tempor incididunt ut labore et dolore magna aliqua.<br>Ut enim ad minim veniam, quis nostrud exercitation ullamco laboris nisi ut aliquip ex ea commodo consequat.</i>"

g +
  geom_textbox(aes(x = 40, y = 10, label = lab_long),
               width = unit(15, "lines"), stat = "unique")

Warning in geom_textbox(aes(x = 40, y = 10, label = lab_long), width = unit(15, : All aesthetics have length 1, but the data has 1461 rows.
ℹ Please consider using `annotate()` or provide this layer with data containing
  a single row.

15. Coordinates

15.1 Flip a plot

15.2 Flip an axis

15.3 Reverse an axis

15.4 Transform an axis

15.5 Circularize a plot

16. Chart Types

16.1 Alternatives to a box plot

16.1.1 Plot of points

16.1.2 Jitter the points

16.1.3 Violin plots

16.1.4 Combine violin with jitter

16.1.5 Combine violin with box plots

16.2 Create rug representation to a plot

16.3 Create a correlation matrix

16.4 Create a contour plot

16.5 Create a heatmap of counts

16.6 Create a ridge plot

17. Ribbons (AUC, CI, etc.)

18. Smoothings

18.1 Add a LOESS or GAM smoothing

18.2 Add a linear fit

18.3 Specify the formula for smoothing

19. Interactive Plots

19.1 Combine `ggplot2` with `shiny`

19.2 Plot.ly via `plotly` and `ggplot2`

19.3 `ggiraph` and `ggplot2`

19.4 Highcharts via `highcharter`

19.5 Echarts via `echarts4r`

19.6 Chart.js via `charter`

20. Remarks, Tipps & Resources

References

Source: https://www.cedricscherer.com/2019/08/05/a-ggplot2-tutorial-for-beautiful-plotting-in-r/;
Top 50 ggplot2 graphs: https://r-statistics.co/Top50-Ggplot2-Visualizations-MasterList-R-Code.html;
ggplot2 extension gallery: https://exts.ggplot2.tidyverse.org/gallery/;
How to extend ggplot2: https://cran.r-project.org/web/packages/ggplot2/vignettes/extending-ggplot2.html.

0 Preparation

1 The Dataset

1.1 Import data

3 The {ggplot2} package

4 A default ggplot

4.1 Change properties of geometries

4.1 Replacing the default ggplot2 theme

5 Axes

5.1 Change axis titles

5.2 Increase space between axis and axis titles.

5.3 Change aesthetics of the axis titles

5.4 Change aesthetics of axis text

5.5 Rotate axis text

5.6 Remove axis text & ticks

5.7 Remove Axis Titles

5.8 Limit axis range

5.9 Force plot to start at the origin

5.10 Axes with same scaling

5.11 Use a function to alter labels

6 Titles

6.1 Add a title

6.2 Make title bold & add a space at the baseline

6.3 Adjust the position of titles

6.4 Use a non-traditional font in your title

6.5 Change spacing in multi-line text

7 Legends

7.1 Turn off the legend

7.2 Remove legend titles

7.3 Change legend position

7.4 Change legend direction

7.5 Change style of the legend title

7.6 Change legend title

7.7 Change order of legend keys

7.8 Change legend labels

7.9 Change background boxes in the legend

7.10 Change size of legend symbols

7.11 Leave a layer of the legend

7.12 Manually adding legend items

7.13 Use other legend styles

8 Backgrounds & grid lines

8.1 Change the panel background color

8.2 Change grid lines

8.3 Change spacing of grid lines

8.4 Change the plot background color

9 Margins

10 Multi-panel plots

10.1 Create a small multiples based on two variables

10.2 Create a small mutilples based on one variables

10.3 Allow axes to roam free

10.4 Use facet_wrap with two variables

10.5 Modify the strip text

10.6 Create a panel of different plots

11. Colors

11.1 Specify single colors

11.2 Asign colors to variables

11.3 Qualitative variables

11.3.1 Manually select qualitative colors

11.3.2 Use built-in qualitative color palettes

11.3.3 Use qualitative colors palettes from extension packages

11.4 Quantitiave variables

11.4.1 Manually set a sequential color scheme

11.4.2 The beautiful Viridis color palette

11.4.3 Extension packages

11.5 Modify color palettes afterwards

12. Themes

12.1 Change the overall plotting themes

12.2 Change the font of all text elelments

12.3 Change the size of all text elements

12.4 Change the size of all lines and rect elements

12.5 Create your own theme

12.6 Update the current theme

13. Lines

13.1 Add horizontal or vertical lines to a plot

13.2 Add a line within a plot

13.3 Add curved lines and arrows to a plot

14. Text

14.1 Add labels to your data

14.2 Add text annotations

14.3 Use markdown and HTML rendering for annotations

15. Coordinates

3 The `{ggplot2}` package

4 A default `ggplot`

4.1 Replacing the default `ggplot2` theme

10.4 Use `facet_wrap` with two variables

19.1 Combine `ggplot2` with `shiny`

19.2 Plot.ly via `plotly` and `ggplot2`

19.3 `ggiraph` and `ggplot2`

19.4 Highcharts via `highcharter`

19.5 Echarts via `echarts4r`

19.6 Chart.js via `charter`