The question is how to reverse operation of separate_rows, as shown in Reverse summary to expand comma separated strings in dataframe
I just adopted the example but aims to realize the opposite purpose: the original data is
df <- tibble(group=c("cat","cat","cat","dog","dog","dog","horse","horse","horse"),
value=c(1,1,1,2,2,2,3,3,3),
list=c("siamese", "burmese", "balinese", "corgi", "sheltie", "collie", "arabian", "friesian", "andalusian"))
group value list
1 cat 1 siamese
2 cat 1 burmese
3 cat 1 balinese
4 dog 2 corgi
5 dog 2 sheltie
6 dog 2 collie
7 horse 3 arabian
8 horse 3 friesian
9 horse 3 andalusian
what I want to do is:
group value list
1 cat 1 siamese,burmese,balinese
2 dog 2 corgi,sheltie,collie
3 horse 3 arabian,friesian,andalusian
