Fix var/std along a dimension with UnitWeights

Project.toml

@@ -1,6 +1,6 @@
 name = "StatsBase"
 uuid = "2913bbd2-ae8a-5f71-8c99-4fb6c76f3a91"
-version = "0.34.11"
+version = "0.34.12"
 authors = ["JuliaStats"]
 
 [deps]

src/moments.jl

@@ -73,7 +73,7 @@ function var(A::AbstractArray{<:Real}, w::AbstractWeights, dim::Int; mean=nothin
 end
 function var(v::AbstractArray{<:Real}, w::UnitWeights, dim::Int; mean=nothing,
                   corrected::Union{Bool, Nothing}=nothing)
-    length(w) == length(v) || throw(DimensionMismatch("Inconsistent array lengths."))
+    size(v, dim) == length(w) || throw(DimensionMismatch("Inconsistent array lengths."))
     corrected = depcheck(:var, :corrected, corrected)
     return var(v; mean, corrected, dims=dim)
 end

test/moments.jl

@@ -481,4 +481,20 @@ end
     end
 end
 
+@testset "weighted var/std along a dimension with UnitWeights" begin
+    x = reshape(1.0:12.0, 3, 4)
+
+    # `UnitWeights` along a dimension must match the unweighted result and must
+    # not erroneously compare the weight length against the total array length.
+    @test var(x, uweights(3), 1; corrected=true) ≈ var(x; dims=1)
+    @test var(x, uweights(4), 2; corrected=true) ≈ var(x; dims=2)
+    @test var(x, uweights(3), 1; corrected=false) ≈ var(x; dims=1, corrected=false)
+    @test std(x, uweights(3), 1; corrected=true) ≈ std(x; dims=1)
+    @test std(x, uweights(4), 2; corrected=true) ≈ std(x; dims=2)
+
+    # A weight vector whose length does not match the reduction dimension errors.
+    @test_throws DimensionMismatch var(x, uweights(4), 1; corrected=true)
+    @test_throws DimensionMismatch var(x, uweights(3), 2; corrected=true)
+end
+
 end # @testset "StatsBase.Moments"