UnitWeights don't have values to return from dataids (#808)

* Added a few basic UnitWeight tests including calling `dataids` explicitly.

* Add explicit dataids special case to pass tests.

* Move tests to existing testset

* Bump patch release

Co-authored-by: Milan Bouchet-Valat <[email protected]>

Author: rofinn

Project.toml

@@ -1,7 +1,7 @@
 name = "StatsBase"
 uuid = "2913bbd2-ae8a-5f71-8c99-4fb6c76f3a91"
 authors = ["JuliaStats"]
-version = "0.33.17"
+version = "0.33.18"
 
 [deps]
 DataAPI = "9a962f9c-6df0-11e9-0e5d-c546b8b5ee8a"

src/weights.jl

@@ -304,6 +304,7 @@ length(wv::UnitWeights) = wv.len
 size(wv::UnitWeights) = tuple(length(wv))
 Base.axes(wv::UnitWeights) = tuple(Base.OneTo(length(wv)))
 
+Base.dataids(::UnitWeights) = ()
 Base.convert(::Type{Vector}, wv::UnitWeights{T}) where {T} = ones(T, length(wv))
 
 @propagate_inbounds function Base.getindex(wv::UnitWeights{T}, i::Integer) where T

test/weights.jl

@@ -117,6 +117,9 @@ end
     @test wv != fweights(fill(1.0, 3))
     @test wv == uweights(3)
     @test wv[[true, false, false]] == uweights(Float64, 1)
+    @test convert(Vector, wv) == ones(3)
+    @test !Base.mightalias(wv, uweights(Float64, 3))
+    @test Base.dataids(wv) == ()
 end
 
 ## wsum