How to mark the number of each rows with a group by

Question

I have a certainly stupid question, but here is how looks my data:

A
A
A
B
B
C
D
D
D
D

All I want to do is that :

A 1
A 2
A 3
B 1
B 2
C 1
D 1
D 2
D 3
D 4

I guess it should be with a group by function and an easy line in R, but I don't find words to find the good topic.

Thanks

Have you checked https://stackoverflow.com/questions/6112803/how-to-create-a-consecutive-index-based-on-a-grouping-variable-in-a-dataframe? — Yach, Apr 24 '20 at 13:28

Matt · Answer 1 · 2020-04-24T13:39:58.467

2

Here is a dplyr solution:

data$numbers <- group_indices(data, letters)

Data:

data <-data.frame(letters= c("A", "A", "A", "B", "B", "C", "D", "D", "D", "D"))

edited Apr 24 '20 at 13:39

answered Apr 24 '20 at 13:34

Matt

1 Answers1