Convert a character variable to a list of list

Question

i want to convert a character variable to a list of list. My character looks like as follows:

\"[[\"a\",2],[\"b\",5]]\"

The expected list

Answer 1

Looks like a JSON list to me, which will make your parsing job pretty simple:

x <- '[["a",2],["b",5]]'

library(jsonlite)
fromJSON(x, simplifyVector=FALSE)
#[[1]]
#[[1]][[1]]
#[1] "a"
#
#[[1]][[2]]
#[1] 2
#
#
#[[2]]
#[[2]][[1]]
#[1] "b"
#
#[[2]][[2]]
#[1] 5

If you want it combined back to columns instead, just let the simplification occur by default:

fromJSON(x)
#     [,1] [,2]
#[1,] "a"  "2" 
#[2,] "b"  "5" 

Answer 2

Here is one possibility via base R,

xx <- '[[a, 2], [b, 5]]'
lapply(split(matrix(gsub('[[:punct:]]', '', unlist(strsplit(xx, ','))), 
                                             nrow = 2, byrow = T), 1:2), 
                                             function(i) list(i[[1]], as.numeric(i[[2]])))

#$`1`
#$`1`[[1]]
#[1] "a"

#$`1`[[2]]
#[1] 2


#$`2`
#$`2`[[1]]
#[1] " b"

#$`2`[[2]]
#[1] 5