some updates for mapreducedim refactor

ext/SparseArraysExt.jl

@@ -38,7 +38,7 @@ end
 # This is the function that does the reduction underlying var/std
 function centralize_sumabs2!(R::AbstractArray{S}, A::SparseMatrixCSC{Tv,Ti}, means::AbstractArray) where {S,Tv,Ti}
     require_one_based_indexing(R, A, means)
-    lsiz = Base.check_reducedims(R,A)
+    lsiz = Base._linear_reduction_length(A, axes(R))
     for i in 1:max(ndims(R), ndims(means))
         if axes(means, i) != axes(R, i)
             throw(DimensionMismatch("dimension $i of `mean` should have indices $(axes(R, i)), but got $(axes(means, i))"))

src/Statistics.jl

@@ -260,7 +260,7 @@ centralize_sumabs2(A::AbstractArray, m, ifirst::Int, ilast::Int) =
 
 function centralize_sumabs2!(R::AbstractArray{S}, A::AbstractArray, means::AbstractArray) where S
     # following the implementation of _mapreducedim! at base/reducedim.jl
-    lsiz = Base.check_reducedims(R,A)
+    lsiz = Base._linear_reduction_length(A, axes(R))
     for i in 1:max(ndims(R), ndims(means))
         if axes(means, i) != axes(R, i)
             throw(DimensionMismatch("dimension $i of `mean` should have indices $(axes(R, i)), but got $(axes(means, i))"))
@@ -339,9 +339,15 @@ over dimensions. In that case, `mean` must be an array with the same shape as
 """
 varm(A::AbstractArray, m::AbstractArray; corrected::Bool=true, dims=:) = _varm(A, m, corrected, dims)
 
-_varm(A::AbstractArray{T}, m, corrected::Bool, region) where {T} =
-    varm!(Base.reducedim_init(t -> abs2(t)/2, +, A, region), A, m; corrected=corrected)
-
+function _varm(A::AbstractArray{T}, m, corrected::Bool, region) where {T}
+    outaxes = Base.reduced_indices(A, region)
+    nmT = Base.nonmissingtype(T)
+    base = typeof(abs2(zero(nmT)) / 2)
+    elT = (T == nmT) ? base : Union{Missing, base}
+    R = Base.mapreduce_similar(A, elT, outaxes)
+    fill!(R, zero(base))
+    return varm!(R, A, m; corrected=corrected)
+end
 varm(A::AbstractArray, m; corrected::Bool=true) = _varm(A, m, corrected, :)
 
 function _varm(A::AbstractArray{T}, m, corrected::Bool, ::Colon) where T

test/runtests.jl

@@ -414,6 +414,9 @@ end
     end
 end
 
+is_missing_or_approx_equals(X, Y) =
+    all(splat((x,y) -> isequal(x, y) || isapprox(x, y)), zip(X, Y))
+
 function safe_cov(x, y, zm::Bool, cr::Bool)
     n = length(x)
     if !zm
@@ -522,9 +525,9 @@ Y = [6.0  2.0;
     @testset "cov with missing" begin
         @test cov([missing]) === cov([1, missing]) === missing
         @test cov([1, missing], [2, 3]) === cov([1, 3], [2, missing]) === missing
-        @test_throws Exception cov([1 missing; 2 3])
-        @test_throws Exception cov([1 missing; 2 3], [1, 2])
-        @test_throws Exception cov([1, 2], [1 missing; 2 3])
+        @test isequal(cov([1 missing; 2 3]), [0.5 missing; missing missing])
+        @test isequal(cov([1 missing; 2 3], [1, 2]), [0.5; missing;;])
+        @test isequal(cov([1, 2], [1 missing; 2 3]), [0.5 missing])
         @test isequal(cov([1 2; 2 3], [1, missing]), [missing missing]')
         @test isequal(cov([1, missing], [1 2; 2 3]), [missing missing])
     end
@@ -633,9 +636,9 @@ end
         @test cor([missing]) === missing
         @test cor([1, missing]) == 1
         @test cor([1, missing], [2, 3]) === cor([1, 3], [2, missing]) === missing
-        @test_throws Exception cor([1 missing; 2 3])
-        @test_throws Exception cor([1 missing; 2 3], [1, 2])
-        @test_throws Exception cor([1, 2], [1 missing; 2 3])
+        @test is_missing_or_approx_equals(cor([1 missing; 2 3]), [1 missing; missing 1])
+        @test is_missing_or_approx_equals(cor([1 missing; 2 3], [1, 2]), [1; missing;;])
+        @test is_missing_or_approx_equals(cor([1, 2], [1 missing; 2 3]), transpose([1, missing]))
         @test isequal(cor([1 2; 2 3], [1, missing]), [missing missing]')
         @test isequal(cor([1, missing], [1 2; 2 3]), [missing missing])
     end