Reorder Boxplot based on function

Introduction

We have already discussed about basic boxplot here. If we wanted to reorder the categorical variables of x axis based on any function such as increasing or decreasing order of median then we use the reorder(..) function.

The reorder function has the following syntax:

reorder(<categorical_variable>, <numerical_variable>, FUNCTION)

Procedure

We will be working with the ggplot2::diamonds dataset, few rows of the data are:

We will create basic boxplot to compare price(continuous) of diamond based on its cut(categorical). We will order the cut (categorical) variable based on median price.

Code

 
library(ggplot2)
# boxplot to compare the price of diamond based on its cut, order by median price
ggplot(data = diamonds) + geom_boxplot(mapping = 
                                         aes(
                                           x = reorder(cut, price, FUN=median), 
                                           y=price
                                           )
                                       )

The output of code is:

Here we can see that the cut is organized based on increasing median price.

Conclusion

Thus we have successfully reordered a boxplot.

References

• https://r4ds.had.co.nz/