In Julia, creating a Weights vector in statsbase - julia

Question

I am playing a bit with Julia.
Consider this function:
function drawValues(fromDistribution, byCount)
#=
inputs:
fromDistribution :
A 2D array
Each element is an array with two elements
The first one is a value, and the second one is the probability of that value
We will draw a value out of this distribution from a random number generator
byCount :
An integer
We draw that many values from the source distribution
=#
values = []
wts = []
for i = 1:length(fromDistribution)
push!(values, fromDistribution[i][1])
push!(wts , fromDistribution[i][2])
end
w = Weights(wts)
res = []
for i = 1:byCount
r = sample(values, w)
push!(res, r)
end
plot(values, wts)
print(res)
end
This throws the error :
ERROR: MethodError: no method matching Weights(::Array{Any,1},
::Float64) Closest candidates are: Weights(::var"#18#V",
::var"#16#S") where {var"#16#S"<:Real, var"#17#T"<:Real,
var"#18#V"<:AbstractArray{var"#17#T",1}} at
/home/hedgehog/.julia/packages/StatsBase/EA8Mh/src/weights.jl:13
Weights(::Any) at
/home/hedgehog/.julia/packages/StatsBase/EA8Mh/src/weights.jl:16
Stacktrace: [1] Weights(::Array{Any,1}) at
/home/hedgehog/.julia/packages/StatsBase/EA8Mh/src/weights.jl:16 [2]
drawValues(::Array{Array{Float64,1},1}, ::Int64) at
/home/hedgehog/LASER.jl:51 [3] top-level scope at REPL[13]:1 [4]
run_repl(::REPL.AbstractREPL, ::Any) at
/build/julia/src/julia-1.5.3/usr/share/julia/stdlib/v1.5/REPL/src/REPL.jl:288
It seems, that the second definition ( Weights(::Array{Any,1})) whould fit. But somehow Julia sees two input arguments?
Please help.
Version details :
Julia Version 1.5.3
Commit 788b2c77c1* (2020-11-09 13:37 UTC)
Platform Info:
OS: Linux (x86_64-pc-linux-gnu)
CPU: AMD Ryzen 7 3700X 8-Core Processor
WORD_SIZE: 64
LIBM: libopenlibm
LLVM:
libLLVM-10.0.1 (ORCJIT, znver2)

Answer 1

Your Vectors have elements of type any.
It should be:
wts = Float64[]
When you write wts=[] it is an equivalent of wts=Any[].
Have a look at the weight methods:
julia> methods(weights)
# 3 methods for generic function "weights":
[1] weights(vs::AbstractArray{T,1} where T<:Real) in StatsBase at c:\JuliaPkg\Julia1.5.3\packages\StatsBase\EA8Mh\src\weights.jl:76
[2] weights(vs::AbstractArray{T,N} where N where T<:Real) in StatsBase at c:\JuliaPkg\Julia1.5.3\packages\StatsBase\EA8Mh\src\weights.jl:77
[3] weights(model::StatisticalModel) in StatsBase at c:\JuliaPkg\Julia1.5.3\packages\StatsBase\EA8Mh\src\statmodels.jl:143
A container having elements of subtype of Real is required.
Similarly for the other containers providing the types is recommended as well:
value = Float64[]
res = Float64[] # or maybe Int[] depending on what your code does