[Rd] stack problem

[Gabor Grothendieck]

One would normally want the original order that so that one can stack
a list, operate on the result and then unstack it back with the
unstacked result having the same ordering as the original.

LL <- list(z = 1:3, a = list())
# since we can't do s <- stack(LL,. drop = FALSE) do this instead:
s <- transform(stack(LL), ind = factor(as.character(ind), levels = names(LL)))
unstack(s)




On Mon, Jun 27, 2016 at 2:55 PM, Michael Lawrence
<lawrence.michael at gene.com> wrote:
> I'll add the drop argument but I'm wondering about the order of the
> levels. Should we set the levels to unique(names(x)) or sort them,
> too?
>
> On Mon, Jun 27, 2016 at 10:39 AM, Gabor Grothendieck
> <ggrothendieck at gmail.com> wrote:
>> stack() seems to drop empty levels.  Perhaps there could be a
>> drop=FALSE argument if one wanted all the original levels.  In the
>> example below, we may wish to retain level "b" in s$ind even though
>> component LL$b has length 0.
>>
>>> LL <- list(a = 1:3, b = list())
>>> s <- stack(LL)
>>> str(s)
>> 'data.frame':   3 obs. of  2 variables:
>>  $ values: int  1 2 3
>>  $ ind   : Factor w/ 1 level "a": 1 1 1
>>
>>
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>>
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tel: 1-877-GKX-GROUP
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