This must be a duplicate but I can't find it. So here goes.
I have a data.frame with two columns. One contains a group and the other contains a criterion. A group can contain many different criteria, but only one per row. I want to identify groups that contain three specific criteria (but that will appear on different rows. In my case, I want to identify all groups that contains the criteria "I","E","C". Groups may contain any number and combination of these and several other letters.
test <- data.frame(grp=c(1,1,2,2,2,3,3,3,4,4,4,4,4),val=c("C","I","E","I","C","E","I","A","C","I","E","E","A"))
> test
grp val
1 1 C
2 1 I
3 2 E
4 2 I
5 2 C
6 3 E
7 3 I
8 3 A
9 4 C
10 4 I
11 4 E
12 4 E
13 4 A
In the above example, I want to identify grp 2, and 4 because each of these contains the letters E, I, and C.
Thanks!