Legends
How can I change the legend title?
Change the label for the aesthetic the legend is drawn for in
labs().
See example
By default your legend label will be the name of the variable that is
mapped to the aesthetic the legend is drawn for. You can change the
title of your legend using labs().
ggplot(mpg, aes(x = hwy, y = cty, color = drv)) +
geom_point() +
labs(color = "Drive train")
If a legend is drawn for multiple aesthetics, you’ll want to update the title for all of them.
#|
# not this
ggplot(mpg, aes(x = hwy, y = cty, color = drv, shape = drv)) +
geom_point() +
labs(color = "Drive train")
# but this
ggplot(mpg, aes(x = hwy, y = cty, color = drv, shape = drv)) +
geom_point() +
labs(color = "Drive train", shape = "Drive train")
How can I increase the spacing between legend keys?
Increase the horizontal space between legend keys with
legend.spacing.x in theme(). This argument
takes a unit object created with grid::unit().
See example
If you have a horizontal legend, generally placed on top or bottom of
the plot with legend.position = "top" or
"bottom", you can change the spacing between legend keys
with legend.spacing.x. You can supply a unit object to this
argument, e.g. unit(1.0, "cm") for 1 cm space between
legend keys. See the documentation for grid::unit() for
more options for units.
ggplot(mpg, aes(x = hwy, y = cty, color = drv)) +
geom_point() +
theme(
legend.position = "bottom",
legend.spacing.x = unit(1.0, "cm")
)
For vertical legends changing legend.spacing.y changes
the space between the legend title and the keys, but not between the
keys, e.g. see the large space between the legend title and keys.
ggplot(mpg, aes(x = hwy, y = cty, color = drv)) +
geom_point() +
theme(legend.spacing.y = unit(3.0, "cm"))
In order to change the space between the legend keys, you can first
make the key size bigger with legend.key.size and then
remove the grey background color with legend.key.
ggplot(mpg, aes(x = hwy, y = cty, color = drv)) +
geom_point() +
theme(
legend.key.size = unit(1.5, "cm"),
legend.key = element_rect(color = NA, fill = NA)
)
Note that the legend title is no longer aligned with the keys with
this approach. You can also shift it over with the hjust
setting of legend.title.
ggplot(mpg, aes(x = hwy, y = cty, color = drv)) +
geom_point() +
theme(
legend.key.size = unit(1.5, "cm"),
legend.key = element_rect(color = NA, fill = NA),
legend.title = element_text(hjust = 0.5)
)
How can I change the key labels in the legend?
If you don’t want to change the levels of the variable the legend is
being drawn for, you can change the key labels at the time of drawing
the plot using the labels argument in the appropriate
scale_*() function,
e.g. scale_colour_discrete() if the legend is for a
discrete variable mapped to the fill aesthetic.
See example
The labels argument of scale_* functions
takes named vectors, which what we would recommend using for relabeling
keys in a legend. Using named lists allows you to declare explicitly
which label is assigned to which level, without having to keep track of
level order.
ggplot(mpg, aes(x = hwy, y = cty, color = drv)) +
geom_point() +
scale_color_discrete(
labels = c("4" = "4-wheel drive",
"f" = "Front-wheel drive",
"r" = "Rear-wheel drive")
)
How can I change the font sizes in the legend?
Set your preference in legend.text for key labels and
legend.title in theme(). In both cases, set
font size in the size argument of
element_text(),
e.g. legend.text = element_text(size = 14).
See example
Font characteristics of a legend can be controlled with the
legend.text and legend.title elements of
theme(). You can use the following for 14 pts text for
legend key labels and 10 pts text for legend title. (Note that this
doesn’t result in a visually pleasing legend, by default ggplot2 uses a
larger font size for the legend title than the legend text.)
ggplot(mpg, aes(x = hwy, y = cty, color = class)) +
geom_point() +
theme(
legend.text = element_text(size = 14),
legend.title = element_text(size = 10)
)
For further customization of legend text, see the documentation for
element_text(), e.g. you can change font colors or font
face as well.
ggplot(mpg, aes(x = hwy, y = cty, color = class)) +
geom_point() +
theme(
legend.text = element_text(size = 14, color = "red"),
legend.title = element_text(size = 10, face = "bold.italic")
)
Colours
How can I change the background colour of plot?
Set the color in panel.background element of
theme() with element_rect(), which takes
arguments like fill (for background fill color) and
colour (for background border color.
See example
You can set the background colour of the plot with
panel.background in theme(). In the following
example the border is made thicker with linewidth = 3
to
ggplot(mpg, aes(x = hwy, y = cty)) +
geom_point() +
theme(panel.background = element_rect(fill = "lightblue", colour = "red", linewidth = 3))
If you want to change the colour of the plotting area but not the
panel where the panel, you can so the same thing with
plot.background.
ggplot(mpg, aes(x = hwy, y = cty)) +
geom_point() +
theme(plot.background = element_rect(fill = "lightblue", colour = "red", linewidth = 3))
Note that ggplot2 has a variety of complete
themes that might already do what you’re hoping to accomplish. For
example, if you prefer a more minimal look to your plots, without the
grey background, you might try theme_minimal().
ggplot(mpg, aes(x = hwy, y = cty)) +
geom_point() +
theme_minimal()
And you can continue customization based on one of these themes.
ggplot(mpg, aes(x = hwy, y = cty)) +
geom_point() +
theme_minimal() +
theme(plot.background = element_rect(colour = "red", linewidth = 3))
You might also find the thematic package useful for simplified theming of your plots.
How can I change the colour NAs are represented with in a plot?
You can set the color of NA with the
na.value argument in the appropriate scale_*()
function, e.g. scale_fill_discrete(na.value = "purple") to
make NAs purple.
See example
Suppose you have the following data frame with two discrete
variables, one of which has an NA.
df <- tibble::tribble(
~group, ~outcome,
1, "yes",
1, "no",
2, "yes",
2, "no",
2, "no",
2, NA
)By default, ggplot2 uses grey to represent NAs.
You can change the color of NA with
scale_fill_discrete() in this case, e.g. make it
purple.
ggplot(df, aes(x = group, fill = outcome)) +
geom_bar() +
scale_fill_discrete(na.value = "purple")
You can also set the color to "transparent". In the plot
below this is shown with theme_minimal() to demonstrate how
that looks on a plot with a transparent background. Note that while this
is possible, setting the colour to transparent as such wouldn’t be
recommended in this particular case as it gives the appearance of a
floating bar.
ggplot(df, aes(x = group, fill = outcome)) +
geom_bar() +
scale_fill_discrete(na.value = "transparent") +
theme_minimal()
Fonts
How can I change the default font size in ggplot2?
Set base_size in the theme you’re using, which is
theme_gray() by default.
See example
The base font size is 11 pts by default. You can change it with the
base_size argument in the theme you’re using. See the complete
theme documentation for more high level options you can set.
ggplot(mpg, aes(x = hwy, y = cty, color = class)) +
geom_point() +
theme_gray(base_size = 18)
If you would like all plots within a session/document to use a
particular base size, you can set it with set_theme(). Run
the following at the beginning of your session or include on top of your
R Markdown document.
set_theme(theme_gray(base_size = 18))How can I change the font size of the plot title and subtitle?
Set your preference in plot.title and
plot.subtitle in theme(). In both cases, set
font size in the size argument of
element_text(),
e.g. plot.title = element_text(size = 20).
See example
Font characteristics of plot titles and subtitles can be controlled
with the plot.title and plot.subtitle elements
of theme(). You can use the following for 20 pts text for
the plot title and 15 pts text for the plot subtitle.
ggplot(mpg, aes(x = hwy, y = cty)) +
geom_point() +
labs(
title = "This is the plot title",
subtitle = "And this is the subtitle"
) +
theme(
plot.title = element_text(size = 20),
plot.subtitle = element_text(size = 15)
)
For further customization of plot title and subtitle, see the
documentation for element_text(), e.g. you can change font
colors or font face as well.
ggplot(mpg, aes(x = hwy, y = cty)) +
geom_point() +
labs(
title = "This is the plot title",
subtitle = "And this is the subtitle"
) +
theme(
plot.title = element_text(size = 20, color = "red"),
plot.subtitle = element_text(size = 15, face = "bold.italic")
)
How can I change the font size of axis labels?
Set your preference in axis.title.
axis.title.x, or axis.title.y in
theme(). In both cases, set font size in the
size argument of element_text(),
e.g. axis.text = element_text(size = 14).
See example
Font characteristics of axis labels can be controlled with
axis.title.x or axis.title.y (or
axis.title if you the same settings for both axes).
ggplot(mpg, aes(x = hwy, y = cty)) +
geom_point() +
labs(
x = "This is HUGE",
y = "This is small"
) +
theme(
axis.title.x = element_text(size = 20),
axis.title.y = element_text(size = 10)
)
For further customization of plot title and subtitle, see the
documentation for element_text(), e.g. you can change font
colors or font face as well.
ggplot(mpg, aes(x = hwy, y = cty)) +
geom_point() +
labs(
x = "This is HUGE",
y = "This is tiny"
) +
theme(
axis.title.x = element_text(size = 20, color = "red"),
axis.title.y = element_text(size = 10, face = "bold.italic")
)
You can also change the size of the axis text (e.g. numbers at the
axis ticks) using axis.text (or axis.text.x
and axis.text.y if you want to set different sizes).
ggplot(mpg, aes(x = hwy, y = cty)) +
geom_point() +
labs(
x = "The axis labels are the same size",
y = "The axis labels are the same size"
) +
theme(
axis.title = element_text(size = 16),
axis.text = element_text(size = 20, color = "blue")
)
What is the default size of geom_text() and how can I
change the font size of geom_text()?
The default font size of geom_text() is about 3.87.
get_geom_defaults(geom_text)$size
#> [1] 3.866058You can change the size using the size argument in
geom_text() for a single plot. If you want to use the same
updated size, you can set this with update_geom_defaults(),
e.g. update_geom_defaults("text", list(size = 6)).
One tricky thing is that this size is in
mm while the size of
element_text() is in pt. If you want to match
geom_text()’s font size to the theme’s size, specify
size.unit = "pt" in geom_text() for a single
plot, or divide the number by the .pt constant variable for
update_geom_defaults(). Please refer to “Font
size” section of the aesthetic specifications for more details.
See example
Suppose you have the following data frame and visualization.
df <- tibble::tribble(
~x, ~y, ~name,
2, 2, "two",
3, 3, "three",
4, 4, "four"
)
ggplot(df, aes(x = x, y = y, label = name)) +
geom_text()
You can set the size of the text with the following.
Or you can map it to the size aesthetic. In
the following size is determined by the x value with
scale_size_identity().
ggplot(df, aes(x = x, y = y, label = name)) +
geom_text(aes(size = x)) +
scale_size_identity()
If you want to use the same updated size for geom_text()
in a series of plots in a session/R Markdown document, you can set use
update_geom_defaults() to update the default size, e.g. if
you want the size for all geom_text() to be 6, use
update_geom_defaults("text", list(size = 6)).