Change Color, Shape & Size of One Data Point in Plot (Base R & ggplot2)
On this page you’ll learn how to set color, shape, and size of a single data point in the R programming language.
The tutorial contains these contents:
Let’s take a look at some R codes in action.
Example Data & Default Plot
The following data is used as basement for this R programming tutorial:
data <- data.frame(x1 = 1:6, # Create example data x2 = 6:1) data # Print example data
Table 1 visualizes that our example data is made up of six rows and two variables.
Example 1: Modify Color, Shape & Size of Individual Data Point in Plot Using Base R
The following code explains how to adjust the color, shape, and size of a single point in a graphic using the basic installation of the R programming language.
Let’s first draw a graph with default specifications:
plot(data$x1, data$x2) # Base R plot with default colors
Figure 1 shows the output of the previously shown syntax – A Base R scatterplot with back points only.
In this example, we change these specifications for the third data point:
plot(data$x1, data$x2, # Base R plot with manual colors col = ifelse(1:nrow(data) == 3, "red", "black"), pch = ifelse(1:nrow(data) == 3, 15, 16), cex = ifelse(1:nrow(data) == 3, 5, 1))
As shown in Figure 2, we have created a scatterplot with different specifications for a single observation by running the previous R syntax.
Example 2: Modify Color, Shape & Size of Individual Data Point in Plot Using ggplot2 Package
We can also change the color, shape, and size of individual points in a ggplot2 plot.
In order to use the functions of the ggplot2 package, we first need to install and load ggplot2:
install.packages("ggplot2") # Install & load ggplot2 package library("ggplot2")
Next, we can create a ggplot2 plot with default specifications:
ggplot(data, aes(x1, x2)) + # ggplot2 plot with default colors geom_point()
As visualized in Figure 3, we have drawn a ggplot2 xy-plot without changed colors, shapes, and point sizes.
We can now adjust these attributes for one particular case by using the col, shape, and size arguments within the geom_point function:
ggplot(data, aes(x1, x2)) + # ggplot2 plot with manual colors geom_point(col = ifelse(1:nrow(data) == 3, "red", "black"), shape = ifelse(1:nrow(data) == 3, 15, 16), size = ifelse(1:nrow(data) == 3, 5, 1))
After executing the previous R programming code the ggplot2 plot shown in Figure 4 has been created. As you can see, a single data point is displayed and highlighted differently compared to the other points.
Video, Further Resources & Summary
Have a look at the following video tutorial of my YouTube channel. I’m explaining the R syntax of this page in the video:
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In addition, you might want to read the related tutorials of statisticsglobe.com. I have published numerous articles about topics such as ggplot2, colors, and graphics in R.
- Change Legend Size in Base R Plot
- Change Font Size of ggplot2 Plot in R
- Change Background Color of ggplot2 Plot
- Plots in R
- R Programming Tutorials
In this tutorial you have learned how to modify color, shape, and size of points in a scatterplot in the R programming language. In case you have additional questions, let me know in the comments section. Furthermore, please subscribe to my email newsletter to receive regular updates on new tutorials.
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