Calculation by group in one column R

Question

group=c("A","A","B","A","B","C","C","A")
y=c(3,4,5,2,1,4,1,2)
df=data.frame(group,y)

using aggregate, I can get the average by

aggregate(df$y, list(df$group), mean)

But my question is: How to do something like : (y_ij-mean_i) where mean_i is the average for group i

thank you.

or `with(df, ave(y, group, FUN=function(x) {x-mean(x)}))` (= `ave(df$y, df$group, FUN=function(x) {x-mean(x)})`) — Cath, Feb 13 '17 at 12:06
or with `dplyr`, `df %>% group_by(group) %>% mutate(mean_y = y - mean(y))` — Ronak Shah, Feb 13 '17 at 12:08

score 2 · Accepted Answer · answered Feb 13 '17 at 12:02

2

We can use ave

 with(df, y- ave(y, group))

answered Feb 13 '17 at 12:02

akrun

1 Answers1