Change bar plot colour in geom_bar with ggplot2 in r

Question

I have the following in order to bar plot the data frame.

c1 <- c(10, 20, 40)
c2 <- c(3, 5, 7)
c3 <- c(1, 1, 1)
df <- data.frame(c1, c2, c3)
ggplot(data=df, aes(x=c1+c2/2, y=c3)) +
  geom_bar(stat="identity", width=c2) +
  scale_fill_manual(values=c("#FF6666"))

I end up having only grey bars: Grey bars for bar plot

I would like to change the color of the bar. I already tried different scale_fill_manual from http://www.cookbook-r.com/Graphs/Colors_(ggplot2)/ but still have grey bars.

Thank you for your help.

Answer 1

If you want all the bars to get the same color ( fill ), you can easily add it inside geom_bar .

ggplot(data=df, aes(x=c1+c2/2, y=c3)) + 
geom_bar(stat="identity", width=c2, fill = "#FF6666")

Add fill = the_name_of_your_var inside aes to change the colors depending of the variable :

c4 = c("A", "B", "C")
df = cbind(df, c4)
ggplot(data=df, aes(x=c1+c2/2, y=c3, fill = c4)) + 
geom_bar(stat="identity", width=c2)

Use scale_fill_manual() if you want to manually the change of colors.

ggplot(data=df, aes(x=c1+c2/2, y=c3, fill = c4)) + 
geom_bar(stat="identity", width=c2) + 
scale_fill_manual("legend", values = c("A" = "black", "B" = "orange", "C" = "blue"))

Answer 2

You could also directly assign your x variable to the fill aesthetic as a factor like this:

c1 <- c(10, 20, 40)
c2 <- c(3, 5, 7)
c3 <- c(1, 1, 1)
df <- data.frame(c1, c2, c3)
library(ggplot2)
ggplot(data=df, aes(x=c1+c2/2, y=c3, fill = factor(c1+c2/2))) +
  geom_bar(stat="identity", width=c2)

When you know what these factors are called (this case: 11.5, 22.5, 43.5), you can simply change its colors using scale_fill_manual with values like this:

library(ggplot2)
ggplot(data=df, aes(x=c1+c2/2, y=c3, fill = factor(c1+c2/2))) +
  geom_bar(stat="identity", width=c2) +
  scale_fill_manual("Legend", values = c("11.5" = "red", "22.5" = "green", "43.5" = "blue"))

^{Created on 2023-01-26 with reprex v2.0.2}