program6

write a R script to construct a box plot showcasing the distribution of continuous variable,grouped by a categorical variable,using ggplot2’s fill aestetics

step1:load the library

#load the library ggplot2
library(ggplot2)

step2:load the dataset

str(iris)

'data.frame':   150 obs. of  5 variables:
 $ Sepal.Length: num  5.1 4.9 4.7 4.6 5 5.4 4.6 5 4.4 4.9 ...
 $ Sepal.Width : num  3.5 3 3.2 3.1 3.6 3.9 3.4 3.4 2.9 3.1 ...
 $ Petal.Length: num  1.4 1.4 1.3 1.5 1.4 1.7 1.4 1.5 1.4 1.5 ...
 $ Petal.Width : num  0.2 0.2 0.2 0.2 0.2 0.4 0.3 0.2 0.2 0.1 ...
 $ Species     : Factor w/ 3 levels "setosa","versicolor",..: 1 1 1 1 1 1 1 1 1 1 ...

head(iris)

  Sepal.Length Sepal.Width Petal.Length Petal.Width Species
1          5.1         3.5          1.4         0.2  setosa
2          4.9         3.0          1.4         0.2  setosa
3          4.7         3.2          1.3         0.2  setosa
4          4.6         3.1          1.5         0.2  setosa
5          5.0         3.6          1.4         0.2  setosa
6          5.4         3.9          1.7         0.4  setosa

step3:construct box plot with grouping

p<-ggplot(data=iris,aes(x=Species,y=Petal.Width,fill=Species))
p

step3.2 add box plot layer

#add a box plot layer
p<-p+geom_boxplot()
p

step 3.3:add labels to the graph

p<-p+labs(title="Box plot of petal width by species",
x="Species",
y="Petal Width")+
theme_minimal()
p