Alternative to mapply to select samples

set.seed(111)
blf <- bl_func()
set.seed(111)
blm <- mapply(sample, bl, kn, replace=TRUE)
all.equal(blf, blm)

Cheers

-----Original Message-----
From: R-help <r-help-bounces at r-project.org> On Behalf Of Chao Liu
Sent: Tuesday, February 2, 2021 3:32 PM
To: r-help <r-help at 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
?

	[[alternative HTML version deleted]]

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 at r-project.org> On Behalf Of Chao Liu
Sent: Tuesday, February 2, 2021 3:32 PM
To: r-help <r-help at 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
?

      [[alternative HTML version deleted]]