R help - Feb 2008 - How to get names of a list into df:s?

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

Try this:

g <- list(a=1:3, b=4:6, c=7:9)
with(stack(g), split(stack(g), ind))

On 21/02/2008, 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
>
>  ______________________________________________
>  R-help at r-project.org mailing list
>  https://stat.ethz.ch/mailman/listinfo/r-help
>  PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
>  and provide commented, minimal, self-contained, reproducible code.
>

-- 
Henrique Dallazuanna
Curitiba-Paran?-Brasil
25? 25' 40" S 49? 16' 22" O

On Thursday 21 February 2008 (19:22:40), Lauri Nikkinen
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))
> 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
The following seems to work:

sapply(names(g), 
	function(n) 
		cbind(
			g[[n]], 
			var1 = rep(n,each=nrow(g[[n]]))
		),
		simplify=FALSE)



Best,
Martin

I don't see any difference 
--- 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
> 
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
> http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained,
> reproducible code.
>

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
>
> ______________________________________________
> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
>


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

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