[R] Named list of data.frames to data.frame with names

[Rui Barradas]

Hello,

There's nothing inelegant in your solution, you're using vectorized 
instructions.
But there's a bug. The argument to rep should be 'each', not 'times'.

l2$name <- rep(names(l), each=sapply(l,nrow))

Hope this helps,

Rui Barradas
Em 30-10-2012 08:16, Mark Payne escreveu:
> Hi,
>
> I very frequently end up in a situation where I have a named list of
> data.frames that I wish to combine. e.g.
>
> l <- list(A=data.frame(x=rnorm(5),
> y=rnorm(5)),
>            B=data.frame(x=rnorm(3),y=rnorm(3)),
>            C=data.frame(x=rnorm(4),y=rnorm(4)),
>            D=data.frame(x=rnorm(7),y=rnorm(7)))
>
> I would like to combine these data.frames into a single data.frame,
> with the column-names. This is easy with rbind and do.call
>
> l2 <- do.call(rbind,l)
>
> However, I would also like l2 to contain a column containing the names
> in the original list? Is there a more elegant way to do this than:
>
> l2 <- do.call(rbind,l)
> l2$name <- rep(names(l),times=sapply(l,nrow))
>
>
> Mark
>
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