Applying a function to each row of a data.table

Question

I looking for a way to efficiently apply a function to each row of data.table. Let\'s consider the following data table:

library(data.table)
library(stringr)         


        

Answer 1

x[, .(a,strsplit(b,' ')), by=1:nrow(x)]

by=nrow(x) is a simple way to force 1 row per by-group