Flattening a delimited composite column

Question

I got a data frame in R where one of the fields is composite (delimited). Here\'s an example of what I got:

users=c(1,2,3)
items=c(\"23 77 49\", \"10 18 28\"         


        

Answer 1

Here is a dplyr solution

users=c(1,2,3)
items=c("23 77 49", "10 18 28", "20 31 84")
df = data.frame(users,items,stringsAsFactors=FALSE)
rbind_all(do(df %.% group_by(users), 
          .f = function(d) data.frame(d[,1,drop=FALSE], 
              items = unlist(strsplit(d[['items']],' ')), 
           stringsAsFactors=FALSE)))

It would be really nice to have an expand function, i.e. the opposite of summarise

eg. if the following would work.

df %.% group_by(users) %.% expand(unlist(strsplit(items,' ')))