Sampling loop from vector

Question

I am playing around to develop a sampling function to do randomization to make days easier:

Question: 
    pln <- 1:80
    bcap <- cumsum(c(20, 12, 16, 16, 16))
    bcap
    [1] 20 32 48 64 80

I want to randomize pln such that 1:20, 21:32, 33:48, 49:64, 65:80, for this example. This might vary for different scenarios.

newpln <- c(sample(1:20), sample(21:32), sample(33:48), 
 sample(49:64), sample(65:80))

I want create a general function where length of bcap can be of any number, however the pln should run 1: max(bcap).

Brock Adams · Accepted Answer · 2011-11-11 00:20:16Z

2

Is this what you want?

> unlist(sapply(mapply(seq, c(1, bcap[1:(length(bcap)-1)]+1), bcap), sample))
 [1] 13 19  4 16 11  2  5 20  9 14 10  3  1  7  6  8 17 12 15 18 27 24 30 32 23 25 28 21 31 26 29 22 39 41 48 36 37 45 42 47 43 38 40 34 35
[46] 44 46 33 60 52 50 58 51 54 62 55 64 61 59 49 63 53 56 57 72 74 76 78 67 69 70 66 73 79 68 80 77 71 75 65

Testing:

> pln <- 1:12
> pln
 [1]  1  2  3  4  5  6  7  8  9 10 11 12

> bcap <- cumsum(c(4, 3, 2, 3))
> bcap
[1]  4  7  9 12

> unlist(sapply(mapply(seq, c(1, bcap[1:(length(bcap)-1)]+1), bcap), sample))
 [1]  4  2  3  1  6  5  7  8  9 12 11 10
> unlist(sapply(mapply(seq, c(1, bcap[1:(length(bcap)-1)]+1), bcap), sample))
 [1]  4  2  3  1  6  5  7  9  8 10 12 11
> unlist(sapply(mapply(seq, c(1, bcap[1:(length(bcap)-1)]+1), bcap), sample))
 [1]  2  3  1  4  7  6  5  8  9 11 10 12

edited Nov 11, 2011 at 0:20

Brock Adams

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answered Nov 10, 2011 at 22:40

kohske

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1 Comment

Brock Adams Over a year ago

actually John (The OP) added that. I just tweaked it, otherwise the suggested edit probably would have been rejected.

Joshua Ulrich · Accepted Answer · 2011-11-11 00:16:01Z

0

You can do this with one call to mapply. You just need an object that contains what's inside the cumsum call of your bcap object.

bvec <- c(20, 12, 16, 16, 16)
mapply(function(x,y) sample(x)+y-x, bvec, cumsum(bvec))

A small example:

bvec <- c(2,1,3,1)
set.seed(21)
unlist(mapply(function(x,y) sample(x)+y-x, bvec, cumsum(bvec)))
# [1] 2 1 3 4 5 6 7

answered Nov 11, 2011 at 0:16

Joshua Ulrich

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Comments

Brian Diggs · Accepted Answer · 2011-11-11 05:57:37Z

0

library("plyr")

unlist(
  llply(
    mlply(
      data.frame(from=c(1,bcap[-length(bcap)]), to=bcap), 
      seq),
    sample),
  use.names = FALSE)

Make a data.frame with each ranges from/to, use that to make a list with the sequences, sample each list, and then combine them together.

UPDATE:

worked for me:

> library("plyr")
> bcap <- cumsum(c(4, 3, 2, 3))
> unlist(llply(mlply(data.frame(from=c(1,bcap[-length(bcap)]), to=bcap),seq),sample),use.names=FALSE)
 [1]  4  2  3  1  7  4  5  6  9  7  8 12  9 11 10
> unlist(llply(mlply(data.frame(from=c(1,bcap[-length(bcap)]), to=bcap),seq),sample),use.names=FALSE)
 [1]  3  1  2  4  5  6  4  7  9  7  8  9 12 10 11
> unlist(llply(mlply(data.frame(from=c(1,bcap[-length(bcap)]), to=bcap),seq),sample),use.names=FALSE)
 [1]  2  3  4  1  6  5  4  7  8  9  7 11 10 12  9

edited Nov 11, 2011 at 5:57

answered Nov 10, 2011 at 22:43

Brian Diggs

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2 Comments

jon Over a year ago

thanks, for some reason - I am getting the following error:Error in do.call(flat, c(args, list(...))) : 'what' must be a character string or a function, you can test on the example in following reply..

Joshua Ulrich Over a year ago

@John: could you be using an out-of-date version of R and/or plyr?

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