ggplot2 point shapes


This R tutorial describes how to change the point shapes of a graph generated using R software and ggplot2 package.


Related Book:


GGPlot2 Essentials for Great Data Visualization in R

Point shapes in R

The different points shapes commonly used in R are illustrated in the figure below :

r point shape

Create some data

mtcars data is used in the following examples.

df <- mtcars[, c("mpg", "cyl", "wt")]
df$cyl <- as.factor(df$cyl)
head(df)
##                    mpg cyl    wt
## Mazda RX4         21.0   6 2.620
## Mazda RX4 Wag     21.0   6 2.875
## Datsun 710        22.8   4 2.320
## Hornet 4 Drive    21.4   6 3.215
## Hornet Sportabout 18.7   8 3.440
## Valiant           18.1   6 3.460

Make sure to convert the column cyl from a numeric to a factor variable.

Basic scatter plots

Create a scatter plot and change point shapes using the argument shape :

library(ggplot2)
# Basic scatter plot
ggplot(df, aes(x=wt, y=mpg)) +
  geom_point()
# Change the point shape
ggplot(df, aes(x=wt, y=mpg)) +
  geom_point(shape=18)
# change shape, color, fill, size
ggplot(df, aes(x=wt, y=mpg)) +
  geom_point(shape=23, fill="blue", color="darkred", size=3)

ggplot2 point shapes in R softwareggplot2 point shapes in R softwareggplot2 point shapes in R software

Note that, the argument fill can be used only for the point shapes 21 to 25

Scatter plots with multiple groups

Change the point shapes, colors and sizes automatically

In the R code below, point shapes, colors and sizes are controlled automatically by the variable cyl :

library(ggplot2)
# Scatter plot with multiple groups
# shape depends on cyl
ggplot(df, aes(x=wt, y=mpg, group=cyl)) +
  geom_point(aes(shape=cyl))
# Change point shapes and colors
ggplot(df, aes(x=wt, y=mpg, group=cyl)) +
  geom_point(aes(shape=cyl, color=cyl))
# change point shapes,  colors and sizes
ggplot(df, aes(x=wt, y=mpg, group=cyl)) +
  geom_point(aes(shape=cyl, color=cyl, size=cyl))

ggplot2 point shapes in R softwareggplot2 point shapes in R softwareggplot2 point shapes in R software

Change point shapes, colors and sizes manually :

The functions below can be used :

  • scale_shape_manual() : to change point shapes
  • scale_color_manual() : to change point colors
  • scale_size_manual() : to change the size of points
# Change colors and shapes manually
ggplot(df, aes(x=wt, y=mpg, group=cyl)) +
  geom_point(aes(shape=cyl, color=cyl), size=2)+
  scale_shape_manual(values=c(3, 16, 17))+
  scale_color_manual(values=c('#999999','#E69F00', '#56B4E9'))+
  theme(legend.position="top")
# Change the point size manually
ggplot(df, aes(x=wt, y=mpg, group=cyl)) +
  geom_point(aes(shape=cyl, color=cyl, size=cyl))+
  scale_shape_manual(values=c(3, 16, 17))+
  scale_color_manual(values=c('#999999','#E69F00', '#56B4E9'))+
  scale_size_manual(values=c(2,3,4))+
  theme(legend.position="top")

ggplot2 point shapes in R softwareggplot2 point shapes in R software

Infos

This analysis has been performed using R software (ver. 3.1.2) and ggplot2 (ver. 1.0.0)


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