R Statistics Cookbook

How to do it...

We will use it to do data wrangling with the very famous mtcars dataset. This dataset contains several attributes (both numeric and categorical) for several car models. We will combine several of the dplyr functions to compute the mean horsepower and mean miles per gallon for each gear type. We will finally sort the result by the mean horsepower.

1. Import the dplyr library:

library(dplyr)

2. The main step is grouping the data by gear; we calculate the mean horsepower, and the sum of the miles per gallon by gear. We then destroy the group structure and we sort the results by mean horsepower using the following code block:

mtcars %>% group_by(am,gear) %>% summarise(mean_hp = mean(hp),sum_mpg = sum(mpg)) %>% ungroup %>% arrange(mean_hp) ...