Why strsplit returns a list

Question

Consider

text <- "who let the dogs out" fooo <- strsplit(text, " ") fooo [[1]] [1] "who" "let" "the" "dogs" "out" 

strsplit output is a list. The first element of the list is a vector containing the words above.

Why does a function behave like this? Is there any case where it will return a list with more than one item?

And I can access the words using

 fooo[[1]][1] [1] "who" 

but is there an easier way?

Answer 1

To your first question, one of the reasons that comes to mind is that it can store result vectors of different lengths in the same object, since it is vectorized over x :

 text <- "who let the dogs out" vtext <- c(text, "who let the") ## > strsplit(text, " ") [[1]] [1] "who" "let" "the" "dogs" "out" > strsplit(vtext, " ") [[1]] [1] "who" "let" "the" "dogs" "out" [[2]] [1] "who" "let" "the" 

If it were to be returned as data.frame , matrix , etc. instead of list , it should be supplemented with additional elements.