Create New Lists Based on List Structure Pattern

Question

I have some data that looks like this:

   dat <- c("Sales","Jim","Halpert","","",
            "Reception","Pam","Beasley","","",
            "Not.Manager","Dwight","Schrute","Bears","Beets","BattlestarGalactica","","",
            "Manager","Michael","Scott","","")

Each "chunk" of data is consecutive with some blanks in between. I want to transform the data into a list of lists that looks like this:

iwant <- c(
           c("Sales","Jim","Halpert"),
           c("Reception","Pam","Beasley"),
           c("Not.Manager","Dwight","Schrute","Bears","Beets","BattlestarGalactica"),
           c("Manager","Michael","Scott")
           )

Suggestions? I am using rvest and stringi. I do not want to add more packages.

Answer 1

You can use rle, split with lapply :

lapply(split(dat, with(rle(dat != ''), 
             rep(cumsum(values), lengths))), function(x) x[x!= ''])

#$`1`
#[1] "Sales"   "Jim"     "Halpert"

#$`2`
#[1] "Reception" "Pam"       "Beasley"  

#$`3`
#[1] "Not.Manager"         "Dwight"    "Schrute"     "Bears"   "Beets"            
#[6] "BattlestarGalactica"

#$`4`
#[1] "Manager" "Michael" "Scott"  

rle part creates group to split on :

with(rle(dat != ''), rep(cumsum(values), lengths))
#[1] 1 1 1 1 1 2 2 2 2 2 3 3 3 3 3 3 3 3 4 4 4 4 4

After split we use lapply to remove any empty elements from each list.