[R] Question: Form a new list with the index replicated equal to the number of elements in that index

[Phil Spector]

Sunny -
    I don't think mapply is needed:

>  lapply(1:length(mylist),function(x)rep(x,length(mylist[[x]])))
[[1]]
[1] 1 1 1

[[2]]
[1] 2

[[3]]
[1] 3 3

 					- Phil Spector
 					 Statistical Computing Facility
 					 Department of Statistics
 					 UC Berkeley
 					 spector at stat.berkeley.edu


On Mon, 13 Sep 2010, Sunny Srivastava wrote:

> Dear R-Helpers,
> I have a list l1 like:
>
> l1[[1]]
> a b c
>
> l1[[2]]
> d
>
> l1[[3]]
> e f
>
> I want an output res like:
>
> res[[1]]
> 1 1 1
>
> res[[2]]
> 2
>
> res[[3]]
> 3 3
>
> Essentially, I want to replicate each index equal to the number of elements
> present in that index.
>
> Below is what I do to accomplish this:
>
> l1 <- list(c("a", "b", "c"), "d", c("e", "f"))
> res <- mapply(rep, seq_along(l1),times=(lapply(l1, length)))
>
> Is there a more elegant way of doing this (possibly using one (l/m)apply
> function)?
>
> Thanks in advance for the help.
>
> Best Regards,
> S.
>
> 	[[alternative HTML version deleted]]
>
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