add rand(::Tuple) #25278

rfourquet · 2017-12-27T10:54:51Z

PR based on #24874, only 2 new commits here.

Knowing the length a compile time gives a big advantage to something like rand(('a', 'b')) over rand(['a', 'b']) (many times faster). This PR implements optimizations for tuples up to length 4, but it could easily be extended. The second commit here shows a use case for this, and I also need that occasionally in my programs.

But this raise one question: what to do for rand((1, 2, 3)). Currently, this calls the array contructor. So it would be a bit inconsistent to have rand(::Tuple) give a scalar except when the tuple is of type Dims. I see few possiblities about this:

live with this small gotcha
make Dims a dedicated types, instead of an alias for tuples of Int. This is a big change, unlikely to happen for 1.0. But I guess most of the time you get a Dims object by calling size on an array, so it doesn't seem to be a no-go in usability.
if we go with WIP/RFC: random unleashed #24912, we could have either rand(Array, (1, 2, 3)) or rand(1, 2, 3) for the construction of an array, i.e. if the size is specified as a tuple, you get to give Array as a parameter.
wait and see if the array versions of rand are disabled, in favor of a Vector constructor (with a Rand iterator).
changing rand to require specifying the type of generated value (currently Float64 is the default) (EDITED)

Thoughts?

Sacha0 · 2017-12-27T19:12:48Z

Interesting collision! :) Something of an analog to the crux of #16029 (recapped in the "tour of the issues" section's first paragraph in #24595 (comment)), which is one of the primary motivations for moving towards #24595. Best!

rfourquet · 2017-12-28T14:27:39Z

Thanks for making this connection! Which reminded me of another possibility to avoid this collision: not having a default type (currently Float64) of generated random values.

I think generating a random value from a tuple would be a useful addition, which is not urgent in itself (could be 1.x), but working-around the collision could involve having to make a breaking change now (like e.g. having rand not default to Float64 anymore), so I will mark for triage (with low priority).

JeffBezanson · 2017-12-28T19:29:19Z

I would say this is already technically a collision:

julia> rand(1:2, 3)
3-element Array{Int64,1}:
 2
 1
 1

julia> rand(2, 3)
2×3 Array{Float64,2}:
 0.290165  0.0238462  0.180859
 0.705275  0.782572   0.682846

(since 2 is iterable)

JeffBezanson · 2017-12-28T19:36:33Z

I think we'll have to go through a process where rand((m,n)) is replaced before we can add this.

JeffBezanson · 2017-12-28T19:44:31Z

From triage: deprecate rand(tuple) to rand(tuple...) so we can add this in 1.0 (at any point).

rfourquet · 2017-12-29T12:38:17Z

deprecate rand(tuple) to rand(tuple...) so we can add this in 1.0 (at any point).

To be clear: only deprecate rand([rng], tuple), or also when the type is specified, like rand([rng], Float64, tuple) ?
The latter doesn't have a collision, e.g with this PR we could even write rand((1, 2, 3), (4, 5)) to have a matrix filled with elements taken from (1, 2, 3).

I would say this is already technically a collision: [...]

deprecating rand(tuple) won't solve this one... shouldn't we deprecate the Float64 default too? It's not clear to me that floats in [1,0) is generally a good default for random numbers. What are the main use cases for it?

Sacha0 · 2017-12-29T17:30:00Z

Deprecating both rand(dims::Integers...) and rand(dims::Tuple) is appealing, convenient as rand(shape) and rand(shape...) sometimes are. To my surprise, a brief skim suggests that a solid majority of rand invocations in test/linalg take either an element type or collection as their first argument, for what that's worth. Best!

rfourquet · 2018-01-04T07:31:08Z

Bump, I need a bit more information to finish this PR (cf. my last comment above). I would also be in favor to deprecate Float64 as the default type for generated values (i.e. requiring specifying S in rand([rng], S, [dims...]).

JeffBezanson · 2018-01-04T16:04:41Z

It seems to me we should only deprecate rand(tuple). I would be very sad to lose rand(m, n) and rand(n) though.

JeffBezanson · 2018-01-10T23:16:06Z

Requires the deprecation to be released first, so moving this to 1.x.

rfourquet · 2018-01-21T03:21:45Z

funny fact: this API conflict was already spotted 3 and a half years ago!

rfourquet · 2018-08-13T15:24:09Z

This is now rebased and should be good for merging. But I'm not clear on how to update the NEWS file, which has only a v1.0.0 title (not a v1.1.0 one).

rfourquet · 2018-08-13T15:27:18Z

stdlib/Random/src/generation.jl

+
+### 2
+
+Sampler(RNG::Type{<:AbstractRNG}, t::Tuple{A,B}, n::Repetition) where {A,B} =


I think that at one point, this signature was in some cases less efficient than Sampler(::Type{RNG}, t::Tuple{A,B}, n::Repetition) where {RNG<:AbstractRNG,A,B}, can there still be occasional observable performance differences ?

vtjnash · 2018-08-16T20:12:05Z

Should this be map(rand, tuple)?

rfourquet · 2018-08-17T13:02:41Z

Should this be map(rand, tuple)?

I don't believe so. Here the proposal is to have rand((1, 2)) produce either 1 or 2, which is expected according to the current API, and useful. A future proposal (in the same line as yesterday's #28705) would be rand(Tuple{Int,Int}) to produce a random tuple of Ints of length 2, which could also be implemented as map(rand, (Int, Int)).

rfourquet · 2018-11-30T16:05:10Z

News added, I will end up merging this soon (was already triaged).

rfourquet · 2018-12-04T15:12:01Z

There was an (hopefully) unrelated error on Appveyor with the Profile test, if someone is interested in investigating: https://ci.appveyor.com/project/JuliaLang/julia/builds/20680685/job/0krm1ke8dp4dwcfc

changes between Julia 1.0 and 1.1, including: - Custom .css-style for compat admonitions. - Information about compat annotations to CONTRIBUTING.md. - NEWS.md entry for PRs #30090, #30035, #30022, #29978, #29969, #29858, #29845, #29754, #29638, #29636, #29615, #29600, #29506, #29469, #29316, #29259, #29178, #29153, #29033, #28902, #28761, #28745, #28708, #28696, #29997, #28790, #29092, #29108, #29782 - Compat annotation for PRs #30090, #30013, #29978, #29890, #29858, #29827, #29754, #29679, #29636, #29623, #29600, #29440, #29316, #29259, #29178, #29157, #29153, #29033, #28902, #28878, #28761, #28708, #28156, #29733, #29670, #29997, #28790, #29092, #29108, #29782, #25278 - Documentation for broadcasting CartesianIndices (#30230). - Documentation for Base.julia_cmd(). - Documentation for colon constructor of CartesianIndices (#29440). - Documentation for ^(::Matrix, ::Number) and ^(::Number, ::Matrix). - Run NEWS-update.jl. Co-authored-by: Morten Piibeleht <morten.piibeleht@gmail.com> Co-authored-by: Fredrik Ekre <ekrefredrik@gmail.com>

Addition of NEWS and compat admonitions for important changes between Julia 1.0 and 1.1, including: - Custom .css-style for compat admonitions. - Information about compat annotations to CONTRIBUTING.md. - NEWS.md entry for PRs #30090, #30035, #30022, #29978, #29969, #29858, #29845, #29754, #29638, #29636, #29615, #29600, #29506, #29469, #29316, #29259, #29178, #29153, #29033, #28902, #28761, #28745, #28708, #28696, #29997, #28790, #29092, #29108, #29782 - Compat annotation for PRs #30090, #30013, #29978, #29890, #29858, #29827, #29754, #29679, #29636, #29623, #29600, #29440, #29316, #29259, #29178, #29157, #29153, #29033, #28902, #28878, #28761, #28708, #28156, #29733, #29670, #29997, #28790, #29092, #29108, #29782, #25278 - Documentation for broadcasting CartesianIndices (#30230). - Documentation for Base.julia_cmd(). - Documentation for colon constructor of CartesianIndices (#29440). - Documentation for ^(::Matrix, ::Number) and ^(::Number, ::Matrix). - Run NEWS-update.jl. Co-authored-by: Morten Piibeleht <morten.piibeleht@gmail.com> Co-authored-by: Fredrik Ekre <ekrefredrik@gmail.com>

rfourquet added performance Must go faster randomness Random number generation and the Random stdlib labels Dec 27, 2017

rfourquet added the triage This should be discussed on a triage call label Dec 28, 2017

JeffBezanson removed the triage This should be discussed on a triage call label Dec 28, 2017

rfourquet added this to the 1.0 milestone Jan 4, 2018

rfourquet mentioned this pull request Jan 6, 2018

deprecate rand(::Tuple) #25429

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JeffBezanson modified the milestones: 1.0, 1.x Jan 10, 2018

cormullion mentioned this pull request Mar 18, 2018

NEWS.md is getting a bit untidy #26508

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rfourquet force-pushed the rf/rand/fromtuples branch from 4c9000d to 1594a1c Compare August 13, 2018 15:08

rfourquet commented Aug 13, 2018

View reviewed changes

rfourquet force-pushed the rf/rand/fromtuples branch from 1594a1c to c15a86c Compare August 13, 2018 16:09

rfourquet changed the title ~~[RFC] add rand(::Tuple)~~ add rand(::Tuple) Aug 16, 2018

rfourquet mentioned this pull request Aug 16, 2018

add rand(::Pair) #28704

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rfourquet added 2 commits November 30, 2018 17:03

add rand(::Tuple)

c271362

LinearAlgebra: delete _rand_pm1! in favor of rand!

3ba74d6

rfourquet force-pushed the rf/rand/fromtuples branch from c15a86c to 3ba74d6 Compare November 30, 2018 16:03

rfourquet mentioned this pull request Nov 30, 2018

deprecate randn((1,2)) #29653

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rfourquet merged commit 5976236 into master Dec 4, 2018

rfourquet deleted the rf/rand/fromtuples branch December 4, 2018 15:09

rfourquet mentioned this pull request Sep 18, 2019

Potentially ambiguous rand behaviour #33309

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add rand(::Tuple) #25278

add rand(::Tuple) #25278

rfourquet commented Dec 27, 2017 •

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rfourquet commented Dec 4, 2018


		### 2

		Sampler(RNG::Type{<:AbstractRNG}, t::Tuple{A,B}, n::Repetition) where {A,B} =

add rand(::Tuple) #25278

add rand(::Tuple) #25278

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