How to use rbindlist(data) instead of do.call(rbind, data) in this case

Question

library(dplyr)
library(data.table)
library(stringr)

test = c('a1b1', 'a2b2', 'a3b3')

result = rbind(c(1,1),
               c(2,2),
               c(3,3))
result
     [,1] [,2]
[1,]    1    1
[2,]    2    2
[3,]    3    3

test2<-do.call(rbind,test %>% str_split('a'))
test3<-do.call(rbind,test2 %>% .[,2] %>% str_split('b'))
test3
     [,1] [,2]
[1,] "1"  "1" 
[2,] "2"  "2" 
[3,] "3"  "3" 

1. do.call(rbind, data) is not equal rbindlist(data) ? data.table::rbindlist is not working. If I want to use rbindlist, what can I do?

rbindlist(test %>% str_split('a'))
Error in rbindlist(test %>% str_split("a")) : 
  Item 1 of input is not a data.frame, data.table or list

Answer 1

If you want to use a similar approach using rbindlist, then you could do something like below. Essentially, you can add in a step to to turn each item in the list into a data.table (but need to transpose first).

library(dplyr)
library(data.table)
library(stringr)

test2 <- rbindlist(test %>% str_split("a") %>% lapply(., function(x)
  as.data.table(t(x))))

test3 <- rbindlist(as.matrix(test2) %>% .[,2] %>% str_split("b") %>% lapply(., function(x)
  as.data.table(t(x))))

Output

test3

   V1 V2
1:  1  1
2:  2  2
3:  3  3