Assign Colors to Continuous Variables in Ggplot2

Change Continuous Color Range in ggplot2 Plot in R (Example)

In this R post you'll learn how to adjust the continuous color range in a ggplot2 plot.

Table of contents:

Here's how to do it!

Example Data, Add-On Packages & Basic Graph

Have a look at the following example data:

                set                .                seed                (                568323                )                # Generate continuous example data                data                <-                data.                frame                (x                =                rnorm(                500                ),                    y                =                rnorm(                500                )                )                head(data)                # Print head of example data              

set.seed(568323) # Generate continuous example data data <- data.frame(x = rnorm(500), y = rnorm(500)) head(data) # Print head of example data

As you can see based on Table 1, our exemplifying data is a data frame containing two columns called "x" and "y".

We also have to install and load the ggplot2 package, in case we want to use the corresponding functions:

install.                packages                (                "ggplot2"                )                # Install ggplot2 package                library(                "ggplot2"                )                # Load ggplot2              

install.packages("ggplot2") # Install ggplot2 package library("ggplot2") # Load ggplot2

Now, we can draw a graphic of our data as follows:

ggp                <-                ggplot(data, aes(x, y, color                =                y)                )                +                # ggplot2 plot with default legend                geom_point(                )                ggp                # Draw ggplot2 scatterplot              

ggp <- ggplot(data, aes(x, y, color = y)) + # ggplot2 plot with default legend geom_point() ggp # Draw ggplot2 scatterplot

Figure 1 shows the output of the previous code – A ggplot2 scatterplot with default color range.

Example: Set New Continuous Color Range in ggplot2 Plot Using colorRampPalette() & scale_colour_gradientn()

The following R programming syntax explains how to change the color range in a ggplot2 plot of continuous data.

As a first step, we have to define the first and last color (i.e. yellow and red) of our color range using the colorRampPalette function:

fun_color_range                <-                colorRampPalette(c(                "yellow",                "red"                )                )                # Create color generating function              

fun_color_range <- colorRampPalette(c("yellow", "red")) # Create color generating function

The previous R code has defined a new function called fun_color_range, which can be used to generate a sequence of colors.

Let's apply this new function to generate a sequence of 20 colors:

my_colors                <-                fun_color_range(                20                )                # Generate color range                #  [1] "#FFFF00" "#FFF100" "#FFE400" "#FFD600" "#FFC900" "#FFBB00" "#FFAE00"                #  [8] "#FFA100" "#FF9300" "#FF8600" "#FF7800" "#FF6B00" "#FF5D00" "#FF5000"                # [15] "#FF4300" "#FF3500" "#FF2800" "#FF1A00" "#FF0D00" "#FF0000"                my_colors                # Print color range              

my_colors <- fun_color_range(20) # Generate color range # [1] "#FFFF00" "#FFF100" "#FFE400" "#FFD600" "#FFC900" "#FFBB00" "#FFAE00" # [8] "#FFA100" "#FF9300" "#FF8600" "#FF7800" "#FF6B00" "#FF5D00" "#FF5000" # [15] "#FF4300" "#FF3500" "#FF2800" "#FF1A00" "#FF0D00" "#FF0000" my_colors # Print color range

As you can see, we have generated 20 hex color codes.

Next, we can use these colors and the scale_colour_gradientn function for our ggplot2 scatterplot. Have a look at the following R code:

ggp                +                # Change colors in ggplot2 plot                scale_colour_gradientn(colors                =                my_colors)              

ggp + # Change colors in ggplot2 plot scale_colour_gradientn(colors = my_colors)

The output of the previous syntax is shown in Figure 2: The values of our scatterplot with a different range of colors.

Video, Further Resources & Summary

I have recently published a video on my YouTube channel, which explains the contents of this article. Please find the video below.

In addition, you may have a look at the other articles on https://www.statisticsglobe.com/. A selection of articles about similar topics such as colors, ggplot2, and graphics in R is shown below.

• Change Color, Shape & Size of One Data Point in Plot (Base R & ggplot2)
• Change Formatting of Numbers of ggplot2 Plot Axis
• Change Background Color of ggplot2 Text Label Annotation in R
• Change Line Width in ggplot2 Plot in R
• Change Display Order of ggplot2 Plot Legend in R
• Change Font Size of ggplot2 Plot in R
• Plotting Data in R
• R Programming Tutorials

You have learned in this tutorial how to change the color range and set a fixed sequence in a ggplot2 plot in the R programming language. Let me know in the comments below, if you have additional comments and/or questions. Furthermore, please subscribe to my email newsletter to receive updates on new tutorials.

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Source: https://statisticsglobe.com/change-continuous-color-range-ggplot2-plot-r

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