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Made WeightVec a subtype of RealVector #248

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Apr 24, 2017
Merged

Made WeightVec a subtype of RealVector #248

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dc17308
Made `WeightVec` a subtype of `RealVector`
rofinn Apr 20, 2017
0248bac
Added a few tests to weights.jl
rofinn Apr 20, 2017
3cfbc21
Changed parameterization of WeightVec.
rofinn Apr 21, 2017
5535cad
Moved constructors out of version check.
rofinn Apr 22, 2017
f4bffc4
Cleaned up WeightVec constructors.
rofinn Apr 23, 2017
e34ebb4
Fixed thrown `MethodError` call in `median(::AbstractArray, ::WeightV…
rofinn Apr 24, 2017
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22 changes: 17 additions & 5 deletions src/weights.jl
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Original file line number Diff line number Diff line change
@@ -1,9 +1,16 @@

###### Weight vector #####

immutable WeightVec{W,Vec<:RealVector}
values::Vec
sum::W
if VERSION < v"0.6.0-dev.2123"
immutable WeightVec{S<:Real, T<:Real, V<:RealVector} <: RealVector{T}
values::V
sum::S
end
else
immutable WeightVec{S<:Real, T<:Real, V<:AbstractVector{T}} <: AbstractVector{T}
values::V
sum::S
end
end

"""
Expand All @@ -12,8 +19,9 @@ end
Construct a `WeightVec` with weight values `vs` and sum of weights `wsum`.
If omitted, `wsum` is computed.
"""
WeightVec{Vec<:RealVector,W<:Real}(vs::Vec,wsum::W) = WeightVec{W,Vec}(vs, wsum)
WeightVec(vs::RealVector) = WeightVec(vs, sum(vs))
function WeightVec{S<:Real, V<:RealVector}(vs::V, s::S=sum(vs))
return WeightVec{S, eltype(vs), V}(vs, s)
end

"""
weights(vs)
Expand All @@ -30,6 +38,7 @@ sum(wv::WeightVec) = wv.sum
isempty(wv::WeightVec) = isempty(wv.values)

Base.getindex(wv::WeightVec, i) = getindex(wv.values, i)
Base.size(wv::WeightVec) = size(wv.values)


##### Weighted sum #####
Expand Down Expand Up @@ -281,6 +290,9 @@ Base.mean{T<:Number,W<:Real}(A::AbstractArray{T}, w::WeightVec{W}, dim::Int) =


###### Weighted median #####
function Base.median(v::AbstractArray, w::WeightVec)
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Shouldn't this method be unnecessary since all you're doing is throwing a MethodError? Presumably without the method, it would also be a MethodError.

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@rofinn rofinn Apr 20, 2017 •
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I needed to added this because this test was failing with a BoundsError instead. It appears that making WeightVec a RealVector allowed it to dispatch to a method in base.

julia> median([4 3 2 1 0], weights(wt))
ERROR: BoundsError: attempt to access 2-element Array{Any,1} at index [3]
 in mapslices(::Base.#median!, ::Array{Int64,2}, ::StatsBase.WeightVec{Int64,Array{Int64,1},Int64}) at ./abstractarray.jl:1619
 in median(::Array{Int64,2}, ::StatsBase.WeightVec{Int64,Array{Int64,1},Int64}) at ./statistics.jl:579```

I figured it was better to manually throw a `MethodError` rather than letting it hit the `BoundsError` in that case.

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Ah, I see. This is fine then. Thanks for clarifying.

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That said, the current behavior isn't that different:

julia> median([4 3 2 1 0], weights([1,2,3,4,5]))
ERROR: MethodError: no method matching start(::StatsBase.WeightVec{Int64,Array{Int64,1}})
Closest candidates are:
  start(::SimpleVector) at essentials.jl:259
  start(::Base.MethodList) at reflection.jl:560
  start(::ExponentialBackOff) at error.jl:107
  ...
Stacktrace:
 [1] append_any(::StatsBase.WeightVec{Int64,Array{Int64,1}}, ::Vararg{StatsBase.WeightVec{Int64,Array{Int64,1}},N} where N) at ./essentials.jl:170
 [2] median(::Array{Int64,2}, ::StatsBase.WeightVec{Int64,Array{Int64,1}}) at ./statistics.jl:619

So I'm not sure this MethodError is really needed. We typically don't throw them for all possible cases that fail.

throw(MethodError(median, (v, w)))
end

function Base.median{W<:Real}(v::RealVector, w::WeightVec{W})
isempty(v) && error("median of an empty array is undefined")
Expand Down
9 changes: 8 additions & 1 deletion test/weights.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -5,10 +5,12 @@ import Compat: view

@test isa(weights([1, 2, 3]), WeightVec{Int})
@test isa(weights([1., 2., 3.]), WeightVec{Float64})

@test isa(weights([1 2 3; 4 5 6]), WeightVec{Int})

@test isa(WeightVec([1, 2, 3], 6), WeightVec{Int})

@test isempty(weights(Float64[]))
@test size(weights([1, 2, 3])) == (3,)

w = [1., 2., 3.]
wv = weights(w)
Expand All @@ -26,6 +28,11 @@ bv = weights(b)
@test sum(bv) === 3
@test !isempty(bv)

ba = BitArray([true, false, true])
sa = sparsevec([1., 0., 2.])

@test sum(ba, wv) === 4.0
@test sum(sa, wv) === 7.0

## wsum

Expand Down