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add rand(::String) #22224

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Jun 15, 2017
Merged

add rand(::String) #22224

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459a126
add rand(::String)
rfourquet May 31, 2017
1deb0c5
test for empty strings (StefanKarpinski) and fix bad usage a GLOBAL_RNG
rfourquet Jun 5, 2017
5e827e9
warn about linear complexity for AbstractString (stevengj)
rfourquet Jun 6, 2017
533dfb3
use O(1) algo for generic AbstractString (StefanKarpinski)
rfourquet Jun 7, 2017
3b97b61
use isvalid instead of try/catch in generic implementation (StefanKar…
rfourquet Jun 13, 2017
fa51ee6
add a missing "or" in doc (stevengj)
rfourquet Jun 13, 2017
a5289a1
add NEWS.md entry
rfourquet Jun 14, 2017
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9 changes: 9 additions & 0 deletions NEWS.md
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Original file line number Diff line number Diff line change
Expand Up @@ -49,6 +49,9 @@ Library improvements
* The function `randn` now accepts complex arguments (`Complex{T <: AbstractFloat}`)
([#21973]).

* The function `rand` can now pick up random elements from strings, associatives
and sets ([#22228], [#21960], [#18155], [#22224]).

* Method lists are now printed as a numbered list. In addition, the source code of a
method can be opened in an editor by entering the corresponding number in the REPL
and pressing `^Q` ([#22007]).
Expand Down Expand Up @@ -743,6 +746,7 @@ Command-line option changes
[#17785]: https://github.com/JuliaLang/julia/issues/17785
[#18012]: https://github.com/JuliaLang/julia/issues/18012
[#18050]: https://github.com/JuliaLang/julia/issues/18050
[#18155]: https://github.com/JuliaLang/julia/issues/18155
[#18159]: https://github.com/JuliaLang/julia/issues/18159
[#18218]: https://github.com/JuliaLang/julia/issues/18218
[#18251]: https://github.com/JuliaLang/julia/issues/18251
Expand Down Expand Up @@ -876,6 +880,7 @@ Command-line option changes
[#21759]: https://github.com/JuliaLang/julia/issues/21759
[#21818]: https://github.com/JuliaLang/julia/issues/21818
[#21825]: https://github.com/JuliaLang/julia/issues/21825
[#21960]: https://github.com/JuliaLang/julia/issues/21960
[#21973]: https://github.com/JuliaLang/julia/issues/21973
[#21974]: https://github.com/JuliaLang/julia/issues/21974
[#22007]: https://github.com/JuliaLang/julia/issues/22007
Expand All @@ -884,3 +889,7 @@ Command-line option changes
[#22064]: https://github.com/JuliaLang/julia/issues/22064
[#22187]: https://github.com/JuliaLang/julia/issues/22187
[#22188]: https://github.com/JuliaLang/julia/issues/22188
[#22224]: https://github.com/JuliaLang/julia/issues/22224
[#22228]: https://github.com/JuliaLang/julia/issues/22228
[#22245]: https://github.com/JuliaLang/julia/issues/22245
[#22310]: https://github.com/JuliaLang/julia/issues/22310
32 changes: 30 additions & 2 deletions base/random.jl
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Expand Up @@ -256,8 +256,9 @@ globalRNG() = GLOBAL_RNG

Pick a random element or array of random elements from the set of values specified by `S`; `S` can be

* an indexable collection (for example `1:n` or `['x','y','z']`), or
* an `Associative` or `AbstractSet` object, or
* an indexable collection (for example `1:n` or `['x','y','z']`),
* an `Associative` or `AbstractSet` object,
* a string (considered as a collection of characters), or
* a type: the set of values to pick from is then equivalent to `typemin(S):typemax(S)` for
integers (this is not applicable to [`BigInt`](@ref)), and to ``[0, 1)`` for floating
point numbers;
Expand Down Expand Up @@ -709,6 +710,33 @@ end
rand(rng::AbstractRNG, r::AbstractArray{T}, dims::Dims) where {T} = rand!(rng, Array{T}(dims), r)
rand(rng::AbstractRNG, r::AbstractArray, dims::Integer...) = rand(rng, r, convert(Dims, dims))

# rand from a string

isvalid_unsafe(s::String, i) = !Base.is_valid_continuation(unsafe_load(pointer(s), i))
isvalid_unsafe(s::AbstractString, i) = isvalid(s, i)
_endof(s::String) = s.len
_endof(s::AbstractString) = endof(s)

function rand(rng::AbstractRNG, s::AbstractString)::Char
g = RangeGenerator(1:_endof(s))
while true
pos = rand(rng, g)
isvalid_unsafe(s, pos) && return s[pos]
end
end

rand(s::AbstractString) = rand(GLOBAL_RNG, s)

## rand from a string for arrays
# we use collect(str), which is most of the time more efficient than specialized methods
# (except maybe for very small arrays)
rand!(rng::AbstractRNG, A::AbstractArray, str::AbstractString) = rand!(rng, A, collect(str))
rand!(A::AbstractArray, str::AbstractString) = rand!(GLOBAL_RNG, A, str)
rand(rng::AbstractRNG, str::AbstractString, dims::Dims) = rand!(rng, Array{eltype(str)}(dims), str)
rand(rng::AbstractRNG, str::AbstractString, d1::Integer, dims::Integer...) = rand(rng, str, convert(Dims, tuple(d1, dims...)))
rand(str::AbstractString, dims::Dims) = rand(GLOBAL_RNG, str, dims)
rand(str::AbstractString, d1::Integer, dims::Integer...) = rand(GLOBAL_RNG, str, d1, dims...)

## random BitArrays (AbstractRNG)

function rand!(rng::AbstractRNG, B::BitArray)
Expand Down
19 changes: 12 additions & 7 deletions test/random.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -319,8 +319,9 @@ for rng in ([], [MersenneTwister(0)], [RandomDevice()])
1:100 => Int,
rand(Int, 100) => Int,
Int => Int,
Float64 => Float64]

Float64 => Float64,
"qwèrtï" => Char,
GenericString("qwèrtï") => Char]
b2 = big(2)
u3 = UInt(3)
for f in [rand, randn, randexp]
Expand All @@ -346,10 +347,13 @@ for rng in ([], [MersenneTwister(0)], [RandomDevice()])
a0 = rand(rng..., C) ::T
a1 = rand(rng..., C, 5) ::Vector{T}
a2 = rand(rng..., C, 2, 3) ::Array{T, 2}
a3 = rand(rng..., C, b2, u3) ::Array{T, 2}
a4 = rand!(rng..., Array{T}(5), C) ::Vector{T}
a5 = rand!(rng..., Array{T}(2, 3), C) ::Array{T, 2}
for a in [a0, a1..., a2..., a3..., a4..., a5...]
a3 = rand(rng..., C, (2, 3)) ::Array{T, 2}
a4 = rand(rng..., C, b2, u3) ::Array{T, 2}
a5 = rand!(rng..., Array{T}(5), C) ::Vector{T}
a6 = rand!(rng..., Array{T}(2, 3), C) ::Array{T, 2}
@test size(a1) == (5,)
@test size(a2) == size(a3) == (2, 3)
for a in [a0, a1..., a2..., a3..., a4..., a5..., a6...]
if C isa Type
@test a isa C
else
Expand All @@ -358,7 +362,8 @@ for rng in ([], [MersenneTwister(0)], [RandomDevice()])
end
end
for C in [1:0, Dict(), Set(), IntSet(), Int[],
GenericDict(Dict()), GenericSet(Set())]
GenericDict(Dict()), GenericSet(Set()),
"", Base.Test.GenericString("")]
@test_throws ArgumentError rand(rng..., C)
@test_throws ArgumentError rand(rng..., C, 5)
end
Expand Down