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How to change legend for multiple histograms using ggplot2 in R?
If we create histogram for multiple categories using ggplot2 then the legend is generated automatically based on the categories. And if we want to change that legend or create a histogram with different legend values having different colors for histograms then scale_fill_manual function can be used as shown in the below example.
Example
Following snippet creates a sample data frame −
Height<-c(sample(140:160,2000,replace=TRUE),sample(165:180,2000,replace=TRUE))
Gender<-c(rep("Female",2000),rep("Male",2000))
df<-data.frame(Gender,Height)
head(df,20)Output
The following dataframe is created −
Gender Height 1 Female 148 2 Female 154 3 Female 149 4 Female 152 5 Female 159 6 Female 150 7 Female 144 8 Female 150 9 Female 154 10 Female 149 11 Female 145 12 Female 159 13 Female 157 14 Female 150 15 Female 152 16 Female 144 17 Female 146 18 Female 142 19 Female 144 20 Female 160
To load ggplot2 package and create histogram of Height for categories in Gender, add the following code to the above snippet −
library(ggplot2) ggplot(df,aes(Height,fill=Gender))+geom_histogram(bins=30)
Output
If you execute all the above given snippets as a single program, it generates the following Output −
To create histogram of Height for categories in Gender by manually defining the legend values and the histograms color, add the following code to the above snippet −
ggplot(df,aes(Height,fill=Gender))+geom_histogram(bins=30)+scale_fill_manual(name="Gender",values=c("blue","green"),labels=c("Ladies","Gents"))
Output
If you execute all the above given snippets as a single program, it generates the following Output −
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