Extracting nth element from a nested list following strsplit - R

Question

I\'ve been trying to understand how to deal with the output of strsplit a bit better. I often have data such as this that I wish to split:

myd         


        

Answer 1

You can assign the length inside sapply, resulting in NA where the current length is shorter than the assigned length.

s <- strsplit(mydata, "/")
sapply(s, function(x) { length(x) <- 3; x[2] })
# [1] "4" "2" "3" NA  "4" NA  NA 

Then you can add a second indexing argument with mapply

m <- max(sapply(s, length))
mapply(function(x, y, z) { length(x) <- z; x[y] }, s, 2, m)
# [1] "4" "2" "3" NA  "4" NA  NA