Concatenating strings using group_by and summarise in r

Question

I am trying to concatenate a column of strings together based on a grouping. I'm using code that seems identical to me to what others have used (e.g. use dplyr to concatenate a column) but it isn't working, and I can't figure out why.

a = tibble(
       x = c(1,2,1,2),
       z = c('1','2','3','4')
   )

a %>% group_by(x) %>% summarise(val=paste(z, collapse=" "))

Gives:

   val
1 1 2 3 4

It acts as if there was only one group. Yet when I do a different function, the grouping works properly:

a %>% group_by(x) %>% tally()
# A tibble: 2 × 2
      x     n
  <dbl> <int>
1     1     2
2     2     2

Any idea what the issue might be?

Answer 1

It could be that plyr package was also loaded and masked the summarise function from dplyr as both of them have the same function name. One option is to use :: to specify the function from the dplyr package

a %>%
   group_by(x) %>%
   dplyr::summarise(val=paste(z, collapse=" "))
# A tibble: 2 x 2
#      x   val
#  <dbl> <chr>
#1     1   1 3
#2     2   2 4