Re: [R] with lapply() how can you retrieve the name of the object

From: jim holtman <jholtman_at_gmail.com>
Date: Fri, 18 Jul 2008 18:57:41 -0400

Is this what you wanted; you would use the 'names' to get the names in the lapply:

> lapply(names(test.list), function(x){
+ cbind(test.list[[x]], var.2=x)
+ })
[[1]]
  var.1 var.2

1     1     a
2     2     a
3     3     a
4     4     a
5     5     a

[[2]]
  var.1 var.2

1    11     b
2    12     b
3    13     b
4    14     b
5    15     b



On Fri, Jul 18, 2008 at 6:31 PM, Jorge Ivan Velez <jorgeivanvelez_at_gmail.com> wrote:
> Dear Andrew,
>
> It's not the best solution but it does what you need:
>
> a <- data.frame(var.1 = 1:5)
> b <- data.frame(var.1 = 11:15)
> test.list <- list(a=a, b=b)
> res=do.call(rbind,test.list)
> res$var.2=substr(rownames(res),1,1)
> rownames(res)=NULL
> res
>
>
> HTH,
>
> Jorge
>
>
> On Fri, Jul 18, 2008 at 6:21 PM, Andrew Yee <yee_at_post.harvard.edu> wrote:
>
>> In the following code, I'd like to be able to create a new variable
>> containing the value of the names of the list.
>>
>>
>> a <- data.frame(var.1 = 1:5)
>> b <- data.frame(var.1 = 11:15)
>>
>> test.list <- list(a=a, b=b)
>>
>> # in this case, names(test.list) is "a" and "b"
>>
>> # and I'd like to use lapply() so that
>> # I get something that looks like
>> # var.1 var.2
>> # 1 a
>> # 2 a
>> # 3 a
>> #etc.
>>
>> new.list <- lapply(test.list, function(x) {x$var.2 <- names(x)
>> x} )
>>
>>
>> # the above clearly doesn't do it. How do you pull out the names of the
>> thing that is being lapplied?
>>
>> Thanks,
>> Andrew
>>
>> [[alternative HTML version deleted]]
>>
>> ______________________________________________
>> 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.
>>
>
> [[alternative HTML version deleted]]
>
> ______________________________________________
> 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

What is the problem you are trying to solve?

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Received on Fri 18 Jul 2008 - 23:00:58 GMT

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