ggplot2 colors : How to change colors automatically and manually? - Easy Guides

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Prepare the data
Simple plots
Use a single color
Change colors by groups
- Default colors
- Change colors manually
- Use RColorBrewer palettes
- Use Wes Anderson color palettes
Use gray colors
Continuous colors
- Gradient colors for scatter plots
- Gradient colors for histogram plots
- Gradient between n colors
Infos

The goal of this article is to describe how to change the color of a graph generated using R software and ggplot2 package. A color can be specified either by name (e.g.: “red”) or by hexadecimal code (e.g. : “#FF1234”). The different color systems available in R are described at this link : colors in R.

In this R tutorial, you will learn how to :

change colors by groups (automatically and manually)
use RColorBrewer and Wes Anderson color palettes
use gradient colors

ToothGrowth and mtcars data sets are used in the examples below.

# Convert dose and cyl columns from numeric to factor variablesToothGrowth$dose <- as.factor(ToothGrowth$dose)mtcars$cyl <- as.factor(mtcars$cyl)head(ToothGrowth)

## len supp dose## 1 4.2 VC 0.5## 2 11.5 VC 0.5## 3 7.3 VC 0.5## 4 5.8 VC 0.5## 5 6.4 VC 0.5## 6 10.0 VC 0.5

head(mtcars)

## mpg cyl disp hp drat wt qsec vs am gear carb## Mazda RX4 21.0 6 160 110 3.90 2.620 16.46 0 1 4 4## Mazda RX4 Wag 21.0 6 160 110 3.90 2.875 17.02 0 1 4 4## Datsun 710 22.8 4 108 93 3.85 2.320 18.61 1 1 4 1## Hornet 4 Drive 21.4 6 258 110 3.08 3.215 19.44 1 0 3 1## Hornet Sportabout 18.7 8 360 175 3.15 3.440 17.02 0 0 3 2## Valiant 18.1 6 225 105 2.76 3.460 20.22 1 0 3 1

Make sure that the columns dose and cyl are converted as factor variables using the R script above.

library(ggplot2)# Box plotggplot(ToothGrowth, aes(x=dose, y=len)) +geom_boxplot()# scatter plotggplot(mtcars, aes(x=wt, y=mpg)) + geom_point()

# box plotggplot(ToothGrowth, aes(x=dose, y=len)) + geom_boxplot(fill='#A4A4A4', color="darkred")# scatter plotggplot(mtcars, aes(x=wt, y=mpg)) + geom_point(color='darkblue')

Default colors

The following R code changes the color of the graph by the levels of dose :

# Box plotbp<-ggplot(ToothGrowth, aes(x=dose, y=len, fill=dose)) + geom_boxplot()bp# Scatter plotsp<-ggplot(mtcars, aes(x=wt, y=mpg, color=cyl)) + geom_point()sp

The lightness (l) and the chroma (c, intensity of color) of the default (hue) colors can be modified using the functions scale_hue as follow :

# Box plotbp + scale_fill_hue(l=40, c=35)# Scatter plotsp + scale_color_hue(l=40, c=35)

Note that, the default values for l and c are : l = 65, c = 100.

Change colors manually

A custom color palettes can be specified using the functions :

scale_fill_manual() for box plot, bar plot, violin plot, etc
scale_color_manual() for lines and points

# Box plotbp + scale_fill_manual(values=c("#999999", "#E69F00", "#56B4E9"))# Scatter plotsp + scale_color_manual(values=c("#999999", "#E69F00", "#56B4E9"))

Note that, the argument breaks can be used to control the appearance of the legend. This holds true also for the other scale_xx() functions.

# Box plotbp + scale_fill_manual(breaks = c("2", "1", "0.5"), values=c("red", "blue", "green"))# Scatter plotsp + scale_color_manual(breaks = c("8", "6", "4"), values=c("red", "blue", "green"))

The built-in color names and a color code chart are described here : color in R.

Use RColorBrewer palettes

The color palettes available in the RColorBrewer package are described here : color in R.

# Box plotbp + scale_fill_brewer(palette="Dark2")# Scatter plotsp + scale_color_brewer(palette="Dark2")

The available color palettes in the RColorBrewer package are :

Use Wes Anderson color palettes

Install and load the color palettes as follow :

# Installinstall.packages("wesanderson")# Loadlibrary(wesanderson)

The available color palettes are :

library(wesanderson)# Box plotbp+scale_fill_manual(values=wes_palette(n=3, name="GrandBudapest"))# Scatter plotsp+scale_color_manual(values=wes_palette(n=3, name="GrandBudapest"))

The functions to use are :

scale_colour_grey() for points, lines, etc
scale_fill_grey() for box plot, bar plot, violin plot, etc

# Box plotbp + scale_fill_grey() + theme_classic()# Scatter plotsp + scale_color_grey() + theme_classic()

Change the gray value at the low and the high ends of the palette :

# Box plotbp + scale_fill_grey(start=0.8, end=0.2) + theme_classic()# Scatter plotsp + scale_color_grey(start=0.8, end=0.2) + theme_classic()

Note that, the default value for the arguments start and end are : start = 0.2, end = 0.8

The graph can be colored according to the values of a continuous variable using the functions :

scale_color_gradient(), scale_fill_gradient() for sequential gradients between two colors
scale_color_gradient2(), scale_fill_gradient2() for diverging gradients
scale_color_gradientn(), scale_fill_gradientn() for gradient between n colors

Gradient colors for scatter plots

The graphs are colored using the qsec continuous variable :

# Color by qsec valuessp2<-ggplot(mtcars, aes(x=wt, y=mpg, color=qsec)) + geom_point()sp2# Change the low and high colors# Sequential color schemesp2+scale_color_gradient(low="blue", high="red")# Diverging color schememid<-mean(mtcars$qsec)sp2+scale_color_gradient2(midpoint=mid, low="blue", mid="white", high="red", space ="Lab" )

Gradient colors for histogram plots

set.seed(1234)x <- rnorm(200)# Histogramhp<-qplot(x =x, fill=..count.., geom="histogram") hp# Sequential color schemehp+scale_fill_gradient(low="blue", high="red")

Note that, the functions scale_color_continuous() and scale_fill_continuous() can be used also to set gradient colors.

Gradient between n colors

# Scatter plot# Color points by the mpg variablesp3<-ggplot(mtcars, aes(x=wt, y=mpg, color=mpg)) + geom_point()sp3# Gradient between n colorssp3+scale_color_gradientn(colours = rainbow(5))

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

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ggplot2 colors : How to change colors automatically and manually? - Easy Guides - Wiki (2024)