rand vs. sample

[StefanKarpinski]

Base Julia provides the rand and rand! functions, which do random sampling over various domains. The StatsBase package provides sample and sample! with partially overlapping functionality. There have been various threads (e.g. this one) where people are discussion additional functionality for one or the other. I'm opening this issue to discuss whether these interfaces should be separate or if they should be merged and if they are to remain separate, to clarify the distinction between rand and sample.

[JeffBezanson]

Looking at the docs, I don't think I see a case where the functions couldn't be combined.

[StefanKarpinski]

Among others, there's this:

julia> using StatsBase

julia> rand(1:3)
1

julia> rand([1:3])
ERROR: no method rand(Array{Int64,1})

julia> sample(1:3)
3

julia> sample([1:3])
3

sample(a) where a is an array could just be a method of rand and since we already support rand(3:100) and a range is just an efficiently stored vector, there is precedent for this.

[StefanKarpinski]

Ah, I misread your comment as "could" rather than "couldn't". So you're in agreement :-)

[StefanKarpinski]

I wonder if the idea of a weighted collection shouldn't be generalized. There's a lot of overlap with multisets and dicts where the values are weights. The features that don't appear in Base's rand function are weights, replacement and ordering. It would be nice if we could arrange things so that there doesn't need to be a separate function just to add those features. We can either backports support for those things into Base or figure out a way to layer support onto the base rand functions in a package.

[andreasnoack]

cc: @lindahua

[lindahua]

I am all for migrating the sample function to base, and merging it with rand. The use of a separate function name in StatsBase is just a stop gap.

cc: @johnmyleswhite

[johnmyleswhite]

I wholeheartedly agree. I would love to see sample in Base.

[porterjamesj]

+1000000 for sample in Base.

[StefanKarpinski]

Well, it's more the other direction we're proposing: using rand in stats to sample things.

[johnmyleswhite]

I thought the idea was to merge the names rand and sample.

[StefanKarpinski]

Yes, that's the idea. It remains to be seen which name will be left at the end.

[johnmyleswhite]

Presumably you're going to keep randn, right? That seems sufficient reason to keep rand over sample?

[jiahao]

I was thinking about that. Samplen is pretty odd.

[lindahua]

Agree to use rand in the place of sample.