Grid customization in ggplot2

By default, ggplot2 creates a major and a minor white grid as shown in the following figure.

library(ggplot2)
ggplot(data = mtcars, aes(x = hp, y = mpg))+ 
  geom_point()

Default ggplot2 grid

Grid customization

Grid customization in ggplot2

The grid aesthetics can be set with the panel.grid component of the theme function. Customize the color, line width and line type with the arguments of the element_line function.

library(ggplot2)

ggplot(data = mtcars, aes(x = hp, y = mpg)) + 
  geom_point() + 
  theme(panel.grid = element_line(color = "#8ccde3",
                                  size = 0.75,
                                  linetype = 2))

You can also customize the major grid and the minor grid individually, as shown in the following sections.

Major grid

The panel.grid.major allows you to customize the major grid of the panel.

library(ggplot2)

ggplot(data = mtcars, aes(x = hp, y = mpg)) + 
  geom_point() + 
  theme(panel.grid.major = element_line(color = "red",
                                        size = 0.5,
                                        linetype = 2))

Major grid in ggplot2

Appending .x or .y to the previous component will allow customizing the vertical and horizontal lines of the major grid.

Vertical lines of the major grid

library(ggplot2)

ggplot(data = mtcars, aes(x = hp, y = mpg)) + 
  geom_point() + 
  theme(panel.grid.major.x = element_line(color = "red",
                                          size = 0.5,
                                          linetype = 2))

Vertical lines of the major grid in ggplot2

Horizontal lines of the major grid

library(ggplot2)

ggplot(data = mtcars, aes(x = hp, y = mpg)) + 
  geom_point() + 
  theme(panel.grid.major.y = element_line(color = "red",
                                          size = 0.5,
                                          linetype = 2))

Horizontal lines of the major grid in ggplot

Minor grid

Minor grid in ggplot2

The panel.grid.minor allows you to customize the minor grid of the panel.

library(ggplot2)

ggplot(data = mtcars, aes(x = hp, y = mpg)) + 
  geom_point() + 
  theme(panel.grid.minor = element_line(color = 2,
                                        size = 0.25,
                                        linetype = 1))

As in the previous section, you can append .x or .y to the theme element.

Minor grid of the X-axis in ggplot2

Vertical lines of the minor grid

library(ggplot2)

ggplot(data = mtcars, aes(x = hp, y = mpg)) + 
  geom_point() + 
  theme(panel.grid.minor.x = element_line(color = 2,
                                          size = 0.25,
                                          linetype = 1))

Minor grid of the Y-axis in ggplot2

Horizontal lines of the minor grid

library(ggplot2)

ggplot(data = mtcars, aes(x = hp, y = mpg)) + 
  geom_point() + 
  theme(panel.grid.minor.y = element_line(color = 2,
                                          size = 0.25,
                                          linetype = 1))

Custom grid breaks

The number of grid breaks can be customized in ggplot for each axis with the breaks argument of the scale_(x|y)_continuous or scale_(x|y)_discrete functions, depending on if the variable of the (x|y)-axis is continuous or discrete.

In this example you can customize the breaks of the Y-axis with the scale_y_continuous function as follows.

library(ggplot2)

ggplot(data = mtcars, aes(x = hp, y = mpg)) + 
  geom_point() + 
  scale_y_continuous(breaks = seq(10, 35, by = 1))

Custom grid breaks in ggplot2 with scale_y_continuous

As the X-axis is also continuous you can make use of the scale_x_continuous to customize the grid breaks of the X-axis.

library(ggplot2)

ggplot(data = mtcars, aes(x = hp, y = mpg)) + 
  geom_point() + 
  scale_x_continuous(breaks = seq(50, 350, by = 25))

Custom grid breaks X-axis with scale_x_continuous

Set minor breaks with minor_breaks argument.

library(ggplot2)

ggplot(data = mtcars, aes(x = hp, y = mpg)) + 
  geom_point() + 
  scale_x_continuous(breaks = seq(50, 350, by = 25),
                     minor_breaks = seq(50, 350, 10))

Minor breaks in ggplot2

Set the number of major breaks with n.breaks argument.

library(ggplot2)

ggplot(data = mtcars, aes(x = hp, y = mpg)) + 
  geom_point() + 
  scale_x_continuous(n.breaks = 20)

The algorithm behind the generation of major breaks may choose a different number than the specified to ensure nice break labels.

Number of breaks in ggplot

Remove grids

The same way you customized each grid (panel.grid, panel.major, panel.major.x, panel.major.y, panel.minor, panel.minor.x, panel.minor.y) you can remove them but setting element_blank instead of element_line.

Remove grid in ggplot2

Remove all grids

library(ggplot2)

ggplot(data = mtcars, aes(x = hp, y = mpg)) + 
  geom_point() + 
  theme(panel.grid = element_blank())

Remove the major grid in ggplot2

Remove the major grid

library(ggplot2)

ggplot(data = mtcars, aes(x = hp, y = mpg)) + 
  geom_point() + 
  theme(panel.grid.major = element_blank())

Remove the minor grid in ggplot2

Remove the minor grid

library(ggplot2)

ggplot(data = mtcars, aes(x = hp, y = mpg)) + 
  geom_point() + 
  theme(panel.grid.minor = element_blank())
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See also