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Rank missing in findmin and findmax of a sparse matrix as dense does #1072

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Merged
ViralBShah merged 2 commits into from
Oct 13, 2026
Merged

Rank missing in findmin and findmax of a sparse matrix as dense does #1072

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5988555
Rank `missing` in `findmin` and `findmax` of a sparse matrix as dense…
ViralBShah Oct 13, 2026
eecc87a
Trim the `missing` test to one case per helper
ViralBShah Oct 13, 2026
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6 changes: 4 additions & 2 deletions src/reductions.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -724,8 +724,10 @@ function _findr(op, A::AbstractSparseMatrixCSC{Tv}, region) where {Tv}
end
end

_isless_fm(a, b) = b == b && ( a != a || isless(a, b) )
_isgreater_fm(a, b) = b == b && ( a != a || isless(b, a) )
# whether `a` replaces the best value so far `b`, by the test of Base's dense `findmin` and
# `findmax`, so that the result agrees with dense on `NaN`, `missing` and signed zeros
_isless_fm(a, b) = Base.isgreater(b, a)
_isgreater_fm(a, b) = isless(b, a)

findmin(A::AbstractSparseMatrixCSC{Tv}, region::Union{Integer,Tuple{Integer},NTuple{2,Integer}}) where {Tv} =
_findr(_isless_fm, A, region)
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4 changes: 4 additions & 0 deletions test/reductions.jl
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Expand Up @@ -221,6 +221,10 @@ end
@test isequal(m(Z, dims=region), m(Array(Z), dims=region))
end
end
# `missing`, which dense ranks above `NaN`
D = Union{Missing,Float64}[NaN missing; 0.0 2.0]
@test isequal(findmin(sparse(D)), findmin(D))
@test isequal(findmax(sparse(D), dims=1), findmax(D, dims=1))
end
for m in [findmax, findmin]
@test_throws ArgumentError m(S, (4, 3))
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