Convert simple data.table to named vector

Question

I need to convert simple data.table to named vector.

Lets say I have data.table

a <- data.table(v1 = c('a', 'b', 'c'), v2 = c(1,2,3))

and I want to get the following named vector

b <- c(1, 2, 3)
names(b) <-  c('a', 'b', 'c')

Is there a way to do it simple

s_baldur · Accepted Answer · 2019-10-02T11:53:35.090

3

Using setNames() in j:

a[, setNames(v2, v1)]
# a b c 
# 1 2 3

edited Oct 02 '19 at 11:53

answered Oct 02 '19 at 11:50

s_baldur

1

ah beat me by 30 seconds – MichaelChirico Oct 02 '19 at 11:51
@MichaelChirico :), btw. is it called `J` or `j`? – s_baldur Oct 02 '19 at 11:52
1

it's `j`; `J` is actually shorthand for the "`J`oin" function that's available in `i`; see ?J – MichaelChirico Oct 02 '19 at 11:54
works faster than Ronak Shah answer – Lodyk Vovchak Oct 02 '19 at 11:55
@user2761282 if speed is very important this should be a bit faster: `setNames(a[["v2"]], a[["v1"]])` – s_baldur Oct 02 '19 at 14:23

score 0 · Answer 2 · answered Oct 02 '19 at 11:48

0

We can use split and unlist to get it as named vector.

unlist(split(a$v2, a$v1))
#a b c 
#1 2 3

answered Oct 02 '19 at 11:48

Ronak Shah

works but a bit slower than the other option – Lodyk Vovchak Oct 02 '19 at 11:55

2 Answers2