[R] How to get names of a list into df:s?

[jim holtman]

Here is one way of doing it:

> lapply(names(g), function(z)cbind(x=g[[z]], var1=z))
[[1]]
  x var1
1 1    a
2 2    a
3 3    a

[[2]]
  x var1
1 4    b
2 5    b
3 6    b

[[3]]
  x var1
1 7    c
2 8    c
3 9    c


On Thu, Feb 21, 2008 at 1:22 PM, Lauri Nikkinen <lauri.nikkinen at iki.fi> wrote:
> R users,
>
> I have a simple lapply question.
>
> g <- list(a=1:3, b=4:6, c=7:9)
> g <- lapply(g, function(x) as.data.frame(x))
> lapply(g, function(x) cbind(x, var1 = rep(names(g), each=nrow(x))[1:nrow(x)]))
>
> I get
>
> $a
>  x var1
> 1 1    a
> 2 2    a
> 3 3    a
>
> $b
>  x var1
> 1 4    a
> 2 5    a
> 3 6    a
>
> $c
>  x var1
> 1 7    a
> 2 8    a
> 3 9    a
>
> And I would like to have
>
> $a
>  x var1
> 1 1    a
> 2 2    a
> 3 3    a
>
> $b
>  x var1
> 1 4    b
> 2 5    b
> 3 6    b
>
> $c
>  x var1
> 1 7    c
> 2 8    c
> 3 9    c
>
> How should I modify my lapply clause to achieve this?
>
> Best regards,
> Lauri
>
> > sessionInfo()
> R version 2.6.1 (2007-11-26)
> i386-apple-darwin8.10.1
>
> locale:
> C
>
> attached base packages:
> [1] stats     graphics  grDevices utils     datasets  methods   base
>
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>



-- 
Jim Holtman
Cincinnati, OH
+1 513 646 9390

What is the problem you are trying to solve?