R ggplot boxplot: order filling variable

Question

I am generating a number of boxplots, each for a different marker, filled by a categorical variable: 'CR' and 'No CR'.

I want the left box in the plot to be the 'No CR'-fill and the right one 'CR'. Like this one:

However, for some plots, I get it the other way around (left 'CR' and right 'No CR')

How can I control (order?) which filling category is left and which one is right?

Here is part of my code:

head(df)

#      ID   y   CR
# 1     1    0  No CR
# 2     2    0  No CR
# 3     3    0  CR
# 4     4    4  No CR

ggplot(df, aes(x = CR, y = y)) +
                  geom_boxplot(aes(fill=CR)) +
                  labs(title="Highly differential peptides") + 
                  scale_fill_manual(values=c("#35978f","#D6604D"))+ 
                  stat_compare_means( label.y = maxadn,size=5)

score 2 · Accepted Answer · answered Apr 26 '22 at 14:06

2

You can relevel your CR variable :

df$CR=factor(df$CR,levels=c("No CR","CR"))

and then try to replot

answered Apr 26 '22 at 14:06

Basti

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Simple and effective :D Thank you so much! – Justalilibit May 04 '22 at 14:50

alan ocallaghan · Answer 2 · 2022-04-26T15:36:36.450

It's nice to include a minimal, reproducible example to make it easier to answer your question thoroughly. First I'll simulate some data:

library("ggplot2")
df <- data.frame( 
    CR = sample(c("CR", "No CR"), 20, replace=TRUE), 
    y = rpois(20, 2) 
)

Then, as explained in this question, you can either set the limits directly:

ggplot(df, aes(x = CR, y = y)) + 
    geom_boxplot(aes(fill=CR)) + 
    scale_fill_manual(values=c("#35978f","#D6604D")) +  
    scale_x_discrete(limits=c("No CR", "CR"))

or use factor levels to control the order:

ggplot(df, aes(x = factor(CR, levels=c("No CR", "CR")), y = y)) + 
    geom_boxplot(aes(fill=CR)) + 
    scale_fill_manual(values=c("#35978f","#D6604D")) +  
    labs(x = "CR")

Without any reordering:

ggplot(df, aes(x = CR, y = y)) + 
    geom_boxplot(aes(fill=CR)) + 
    scale_fill_manual(values=c("#35978f","#D6604D"))

R ggplot boxplot: order filling variable

2 Answers2