[R] Converting a list to a data frame

Tóth Dénes
Wed, 02 May 2018 19:30:37 -0000

On 05/02/2018 07:11 PM, Kevin E. Thorpe wrote:
> I suspect this is pretty easy, but I'm having trouble figuring it out.
> Basically, I have a list of data frames such as the following example:
>
> list(A=data.frame(x=1:2, y=3:4),B=data.frame(x=5:6,y=7:8))
>
> I would like to turn this into  data frame where the list elements are
> essentially rbind'ed together and the element name becomes a new
> variable. For example, I would like to turn the list above into a data
> frame that looks like this:
>
>
data.frame(type=c("A","A","B","B"),x=c(1:2,5:6),y=c(3:4,7:8))
>
> Appreciate any pointers.

Hi Kevin,

data.table::rbindlist does exactly what you want in a very efficient way:

library(data.table)
dat <- list(A=data.frame(x=1:2, y=3:4),B=data.frame(x=5:6,y=7:8))
rbindlist(dat, idcol = "type")

Regards,
Denes


>
> Kevin
>