How do I add summary-statistics values to each row of a data frame?

Question

I would like to know a tidyverse way to add summary statistics back to each row of a dataframe.

The code below works, but should be a quicker way out there, right?

library("tidyverse")
data <- (iris)

means <- iris %>%
  group_by(Species) %>%
  summarise(
    Sepal.Length = mean(Sepal.Length),
    Sepal.Width = mean(Sepal.Width)
  )

data <- merge(data, means, by = "Species")

Answer 1

One way to do this would be to use mutate.

library("tidyverse")
data <- (iris)

data<-data %>% 
  group_by(Species) %>% 
  mutate(Sepal.Length.y=mean(Sepal.Length), Sepal.Width.y=mean(Sepal.Width)) 

So this is very similar to what you had before but cuts out a few steps. If you want to rearrange the order of the columns you can reorder them. Also, I would recommend changing the column names from Sepal.Length and Sepal.Width in your post but if you don't specify a unique name r will just put a .y on them to make them unique. Hope this helps.