[R] reorder a list

[Greg Snow]

Oops, I combined 2 ideas (by chance it still worked), the last line
should have been one of the following:

split( rep( seq_along(A1), sapply(A1,length) ), tmp )

split( as.numeric(sub('\\..*$','',names(tmp))), tmp )

On Tue, Jul 8, 2014 at 11:41 AM, Greg Snow <538280 at gmail.com> wrote:
> Here is another approach inspired by Jim's answer:
>
>> names(A1) <- paste0(seq_along(A1),'.')
>> tmp <- unlist(A1)
>> split( rep( seq_along(A1), sapply(A1,length) ), as.numeric(sub('\\..+$','',tmp)) )
> $`1`
> [1] 1
>
> $`2`
> [1] 1 2
>
> $`3`
> [1] 1
>
> $`4`
> [1] 1 2 4
>
> $`5`
> [1] 2 4
>
> $`13`
> [1] 4
>
> $`23`
> [1] 3
>
> On Tue, Jul 8, 2014 at 11:10 AM, jim holtman <jholtman at gmail.com> wrote:
>> Try this:
>>
>>> A1<-list(c(1:4),c(2,4,5),23,c(4,5,13))
>>>
>>> # unlist with the list number
>>> result <- do.call(rbind, sapply(seq(length(A1)), function(.indx){
>> +     cbind(value = A1[[.indx]], index = .indx)
>> + }))
>>>
>>> ans <- split(result[, 2], result[, 1])
>>> ans
>> $`1`
>> [1] 1
>>
>> $`2`
>> [1] 1 2
>>
>> $`3`
>> [1] 1
>>
>> $`4`
>> [1] 1 2 4
>>
>> $`5`
>> [1] 2 4
>>
>> $`13`
>> [1] 4
>>
>> $`23`
>> [1] 3
>>
>>
>>
>> Jim Holtman
>> Data Munger Guru
>>
>> What is the problem that you are trying to solve?
>> Tell me what you want to do, not how you want to do it.
>>
>>
>> On Tue, Jul 8, 2014 at 12:39 PM, Lorenzo Alfieri <alfios17 at hotmail.com>
>> wrote:
>>
>>> Hi,
>>> I'm trying to find a way to reorder the elements of a list.
>>> Let's say I have a list like this:
>>> A1<-list(c(1:4),c(2,4,5),23,c(4,5,13))
>>>
>>> > A1
>>> [[1]]
>>> [1] 1 2 3 4
>>>
>>> [[2]]
>>> [1] 2 4 5
>>>
>>> [[3]]
>>> [1] 23
>>>
>>> [[4]]
>>> [1]  4  5 13
>>>
>>> All the elements included in it are values, while each sublist is a time
>>> index
>>> Now, I'd like to reorder the list (without looping) so to obtain one
>>> sublist for each value, which include all the time indices where each value
>>> appears.
>>> In other words, the result should look like this:
>>> >A2
>>> [[1]]
>>> [1] 1
>>>
>>> [[2]]
>>> [1] 1 2    #because value "2" appears in the time index [[1]] and [[2]] of
>>> A1
>>>
>>> [[3]]
>>> [1] 1
>>>
>>> [[4]]
>>> [1] 1 2 4
>>>
>>> [[5]]
>>> [1] 2 4
>>>
>>> [[13]]
>>> [1] 4
>>>
>>> [[23]]
>>> [1] 3
>>>
>>> Any suggestion?
>>> Thanks
>>> Alfio
>>>
>>>
>>>         [[alternative HTML version deleted]]
>>>
>>> ______________________________________________
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>>> 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.
>
>
>
> --
> Gregory (Greg) L. Snow Ph.D.
> 538280 at gmail.com



-- 
Gregory (Greg) L. Snow Ph.D.
538280 at gmail.com