[R] writing elements in list as a data frame

[jim holtman]

Try this:

> sls <- list(a=matrix(sample(10), ncol=2, dimnames=list(NULL, c('x', 'y'))),
+     b=matrix(sample(16), ncol=2, dimnames=list(NULL, c('x', 'y'))))
> sls
$a
     x  y
[1,] 8  2
[2,] 9 10
[3,] 4  1
[4,] 5  7
[5,] 3  6

$b
      x  y
[1,]  4 14
[2,]  3 15
[3,] 16  5
[4,]  1  9
[5,]  8  7
[6,] 10  2
[7,] 12 13
[8,] 11  6

> # create output matrix
> do.call('rbind', lapply(names(sls), function(.name){
+     data.frame(sls[[.name]], Name=.name)
+ }))
    x  y Name
1   8  2    a
2   9 10    a
3   4  1    a
4   5  7    a
5   3  6    a
6   4 14    b
7   3 15    b
8  16  5    b
9   1  9    b
10  8  7    b
11 10  2    b
12 12 13    b
13 11  6    b
>
>


On 9/5/07, Srinivas Iyyer <srini_iyyer_bio at yahoo.com> wrote:
> Dear R-helpers,
> Lists in R are stumbling block for me.
>
> I kindly ask you to help me able to write a
> data-frame.
>
> I have a list of lists.
>
> > sls[1:2]
> $Andromeda_maya1
>       x   y
> [1,] 369 103
> [2,] 382 265
> [3,] 317 471
> [4,] 169 465
> [5,] 577 333
>
> $Andromeda_maya2
>        x   y
>  [1,] 173 507
>  [2,] 540 395
>  [3,] 268 143
>  [4,] 346 175
>  [5,] 489  91
>
> I want to be able to write a data.frame like the
> following:
> X   Y     Name
> 369 103  Andromeda_maya1
> 382 265  Andromeda_maya1
> 317 471  Andromeda_maya1
> 169 465  Andromeda_maya1
> 577 333  Andromeda_maya1
> 173 507  Andromeda_maya2
> 540 395  Andromeda_maya2
> 268 143  Andromeda_maya2
> 346 175  Andromeda_maya2
> 489  91  Andromeda_maya2
>
> Is there a way to convert this list-of-list into a
> data.frame.
>
> Thanks
> srini
>
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> and provide commented, minimal, self-contained, reproducible code.
>


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

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