RandomExtensions

rand([rng=GLOBAL_RNG], [S], [C...]) # RandomExtensions

Pick a random element or collection 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']),
• an AbstractDict 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, and to $[0, 1)$ for floating point numbers;
• a Distribution object, e.g. Normal() for a normal distribution (like randn()), or CloseOpen(10.0, 20.0) for uniform Float64 numbers in the range $[10.0, 20.0)$;
• a make object, which can be e.g. make(Pair, S1, S2) or make(Complex, S1, S2), where S1 and S2 are one of the specifications above; Pair or Complex can optionally be given as concrete types, e.g. make(ComplexF64, 1:3, Int) to generate ComplexF64 instead of Complex{Int}.

S usually defaults to Float64.

If C... is not specified, rand produces a scalar. Otherwise, C can be:

• a set of integers, or a tuple of Int, which specify the dimensions of an Array to generate;
• (Array, dims...): same as above, but with Array specified explicitely;
• (p::AbstractFloat, m::Integer, [n::Integer]), which produces a sparse array of dimensions (m, n), in which the probability of any element being nonzero is independently given by p;
• (String, [n=8]), which produces a random String of length n; the generated string consists of Char taken from a predefined set like randstring, and can be specified with the S parameter;
• (Dict, n), which produces a Dict of length n; if Dict is given without type parameters, then S must be specified;
• (Set, n) or (BitSet, n), which produces a set of length n;
• (BitArray, dims...), which produces a BitArray with the specified dimensions.

For Array, Dict and Set, a less abstract type can be specified, e.g. Set{Float64}, to force the type of the result regardless of the S parameter. In particular, in the absence of S, the type parameter(s) of the container play the role of S; for example, rand(Dict{Int,Float64}, n) is equivalent to rand(make(Pair, Int, Float64), Dict, n).

Examples

julia> rand(Int, 2)
2-element Array{Int64,1}:
 1339893410598768192
 1575814717733606317

julia> rand(MersenneTwister(0), Dict(1=>2, 3=>4))
1=>2

julia> rand("abc", String, 12)
"bccaacaabaac"

julia> rand(1:10, Set, 3)
Set([3, 8, 6])

julia> rand(1:10, Set{Float64}, 3)
Set([10.0, 5.0, 6.0])