CODEWITHSUNDEEP
rggplot2
crazyhottommy
crazyhottommy

Reputation: 310

ggplot boxplot for multiple columns with a factor

I am new to ggplot2, I want to plot boxplot of multiple numerical columns in the same plot, and group the boxplot by a factor from the last column the header of the dataframe is like:

id var1 var2 var3 factor

I know I can do:

ggplot(df,aes(x=factor,y=var1)+geom_boxplot()

For each variable.

How can I plot them together with ggplot2? The base graphics utility boxplot(df[,-c(id,factor)] will plot them together.

Upvotes: 2

Views: 23210

Answers (2)

rnso
rnso

Reputation: 24535

Following works "to plot boxplot of multiple numerical columns in the same plot, and group the boxplot by a factor": 

mm = melt(df, id=c('id','factor.col'))
ggplot(mm)+geom_boxplot(aes(x=paste(variable,factor.col,sep="_"), y=value))

enter image description here

Data: 

> df
   id          var1       var2       var3 factor.col
1   1  0.0562941632  1.3055892 -1.7553986          c
2   2  0.3187487914 -0.6434729  0.7582403          a
3   3 -1.0120881740  0.3898366  0.4790115          c
4   4 -0.7576871261  0.9474247  0.2180341          b
5   5 -0.2895981608  0.2388043 -0.4407693          a
6   6  0.0005306311  0.9494667 -0.2604795          c
7   7  0.2022893934 -0.3095420 -1.9483369          c
8   8 -0.8179580833 -0.7891642  0.7662824          b
9   9 -0.7553554525  0.2734337 -0.7145471          b
10 10  0.4206429078 -0.6171774  0.6274320          c
>

Following can also be used: 

ggplot(mm)+geom_boxplot(aes(x=variable, y=value))+facet_grid(.~factor.col)

enter image description here

Upvotes: 11

Jase_
Jase_

Reputation: 1196

When you use ggplot2 the layout of your data needs to be a little different to how you would have it for the base graphics

#Your sample data...
df= data.frame(id = 1:10,
           var1 = rnorm(10),
           var2 = rnorm(10),
           var3= rnorm(10),
           factor.col= LETTERS[1:10]
)
# Use the reshape2 package to merge the columns by id and factor.col
library(reshape2)
df_long <- melt(df, id=c("id","factor.col"))
# And now plot the boxplots
library(ggplot2)
ggplot(df_long,aes(x=factor.col,y=value)) + geom_boxplot()

Upvotes: 1

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