[R] Alternative to mapply to select samples

[Chao Liu]

Thank you for your input, Petr. I will give it a try.

Best,

Chao
ᐧ

On Wed, Feb 3, 2021 at 4:32 AM PIKAL Petr <petr.pikal using precheza.cz> wrote:

> Hi
>
> I am not sure if I understand your function but simple mapply gives you
> probably the same result and may be quicker.
>
> > set.seed(111)
> > blf <- bl_func()
> > set.seed(111)
> > blm <- mapply(sample, bl, kn, replace=TRUE)
> > all.equal(blf, blm)
> [1] TRUE
>
> > Cheers
> Petr
>
> > -----Original Message-----
> > From: R-help <r-help-bounces using r-project.org> On Behalf Of Chao Liu
> > Sent: Tuesday, February 2, 2021 3:32 PM
> > To: r-help <r-help using r-project.org>
> > Subject: [R] Alternative to mapply to select samples
> >
> > Dear R-Help,
> >
> > I created a mapply function to select samples from a dataset but are
> there
> > any faster ways to do it by avoiding mapply because it is slow and I
> have a
> > larger dataset? My goal is to use more matrix / vector operations and
> less
> > in terms of lists (the format of the output can be flexible). Ideally, I
> > would like to stick to base R methods without the aid of parallel process
> > or packages. Any ideas will be appreciated!
> >
> > #A list of a set of data to be selected
> > bl <- list(list(c(1, 2),c(2, 3), c(3, 4), c(4, 5), c(5, 6), c(6, 7), c(7,
> > 8), c(8, 9)),
> >          list(c(1, 2, 3), c(2, 3, 4), c(3, 4, 5), c(4, 5, 6), c(5, 6, 7),
> > c(6, 7, 8)),
> >          list(c(1, 2, 3, 4, 5), c(2, 3, 4, 5, 6), c(3, 4, 5, 6, 7), c(4,
> 5,
> > 6, 7, 8), c(5, 6, 7, 8, 9)))
> > #Number of elements to be selected
> > kn <- c(5, 4, 3)
> > #Total number of elements in each set
> > nb <- c(8, 6, 5)
> > #This output a list but preferably I would like a matrix
> > bl_func <- function() mapply(function(x, y, z) {
> >   x[sample.int(y, z, replace = TRUE)]
> > }, bl, nb, kn, SIMPLIFY = FALSE)
> >
> > Best,
> >
> > Chao
> > ᐧ
> >
> >       [[alternative HTML version deleted]]
> >
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