[Bioc-devel] Subsetting Lists by Lists

[Ryan]

That won't work if any vector has fewer than 5 elements. Maybe

lapply(x, head, n=5)

would work?

On Tue Apr  1 09:24:51 2014, Cook, Malcolm wrote:
> in the mean time,
>
> lapply(`[`,x,IntegerList(1:5))
>
> ??
>
>   >-----Original Message-----
>   >From: bioc-devel-bounces at r-project.org [mailto:bioc-devel-bounces at r-project.org] On Behalf Of Michael Lawrence
>   >Sent: Tuesday, April 01, 2014 9:21 AM
>   >To: bioc-devel at r-project.org
>   >Subject: [Bioc-devel] Subsetting Lists by Lists
>   >
>   >Mostly to Herve:
>   >
>   >Sometimes we want to pluck the first 1, or 10, or whatever elements from
>   >each element of a list. If I had a list 'x', I thought I could do this with:
>   >
>   >x[IntegerList(1:5)]
>   >
>   >But it only gives elements 1:5 from x[[1]], not each element of 'x'. In
>   >other words, I thought the index would be repped out. Instead, 'x' is
>   >subset to the length of 'i', and I'm not sure if that makes sense?
>   >
>   >But maybe what we really want are pluckHead/Tail, which would be robust to
>   >the case that < n elements are in an element. And of course a more general
>   >pluck(x, i) to select 'i' from each element, but I wanted the line above to
>   >do that.
>   >
>   >Michael
>   >
>   >	[[alternative HTML version deleted]]
>   >
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