This article describes how to use the colorRampPalette() R function to expand color palettes. We’ll provide practical example with ggplot2.
The color scales defined in the RColorBrewer and in other packages, such as viridis, have a fixed number of colors.
For example you have 8 colors in the
Set2 brewer palette. Consequently, if your data contain more than 8 groups, ggplot2 will return a warning like this:
1: In brewer.pal(n, pal) : n too large, allowed maximum for palette Set2 is 8 Returning the palette you asked for with that many colors
For example, type this R code:
df <- iris[1:18, ] df$name <- 1:nrow(df) library(ggplot2) ggplot(df) + geom_col(aes(name, Sepal.Length, fill = factor(Sepal.Length))) + scale_fill_brewer(palette="Set2") + theme_minimal() + theme(legend.position = "top")
A solution is to use the function
colorRampPalette() which can extend any list of colors:
library(RColorBrewer) # Define the number of colors you want nb.cols <- 18 mycolors <- colorRampPalette(brewer.pal(8, "Set2"))(nb.cols) # Create a ggplot with 18 colors # Use scale_fill_manual ggplot(df) + geom_col(aes(name, Sepal.Length, fill = factor(Sepal.Length))) + scale_fill_manual(values = mycolors) + theme_minimal() + theme(legend.position = "top")
In conclusion, this article describes how to expand color palettes in R.
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Amazing tutorial.. saved my life keep spreading the knowledge!! God bless you!
Thank you for the positive feedback, highly appreciated!
I want to use colorRampPalette() to get 15 colour legend and gradient for a heatmap using pheatmap package. Can you help me out regarding that?
Thank you for this tip! It was really useful!!
Thank you, Thank you. I was stuck.