How to extract the outliers of a boxplot in R?

To extract the outliers of a boxplot, we can use out function along with the boxplot function. For example, if we have a vector called X which contains some outliers then we can extract those outliers by using the command given below −

boxplot(df$X,plot=FALSE)$out

This command will not create a plot as plot is set to FALSE.

Example

Following snippet creates a sample data frame −

df=data.frame(x=rlnorm(25))
df

The following dataframe is created −

     x
1  0.5699270
2  3.5812629
3  0.3507882
4  0.1400328
5  0.7239948
6  2.5494114
7  3.1243611
8  5.3207739
9  0.1672539
10 7.6235529
11 0.4950263
12 1.1713592
13 1.6590328
14 0.4404338
15 0.1354914
16 0.6192213
17 1.0878246
18 0.4084088
19 0.3980110
20 1.3915935
21 0.8679156
22 1.5447279
23 0.9476949
24 0.4036890
25 3.6822067

To create boxplot of x, add the following code to the above snippet −

df=data.frame(x=rlnorm(25))
boxplot(df$x)

Output

If you execute all the above given snippets as a single program, it generates the following output: −

To extract outliers from above boxplot, add the following code to the above snippet −

df=data.frame(x=rlnorm(25))
boxplot(df$x,plot=FALSE)$out

Output

If you execute all the above given snippets as a single program, it generates the following output: −

[1] 3.581263 5.320774 7.623553 3.682207