change the color for bars in geom bar in ggplot

Question

Hi, my problem is i want to fill bars in differnt colors, but if i use color or fill it gives blue scale in bars. How to provide different colors or default colors for each bar?

Answer 1

Hi @radha,

You can have 2 types of a bar chart in ggplot ( Continuos or discrete )

For Continuous, You have 2 types of color scales, default and Viridis.

ggplot(mpg, aes(displ, hwy, fill = displ)) + geom_bar(stat = "identity")

ggplot(mpg, aes(displ, hwy, fill = displ)) + geom_bar(stat = "identity") + scale_fill_continuous(type = "viridis")

You can see below colors,

  

     

For discrete bars, you can provide colors or default colors by R.

You can change the palette using scale_colour_brewer(palette = "Set1,2, ... ") to chnage the colors.

Alternative using scale_fill_manual(values = c("red","blue","green","yellow"))

Answer 2

Hi,

You can use the geom_bar() function to change the colors of bars as shown below.

df <- data.frame(dose=c("D0.5", "D1", "D2"), len=c(4.2, 10, 29.5)) 
head(df)
library(ggplot2) 
# Basic barplot 
p<-ggplot(data=df, aes(x=dose, y=len)) + geom_bar(stat="identity")