Specialize findmax/findmin on SparseVector, fixes JuliaLang#42823 (Ju…

…liaLang#42825)

stdlib/SparseArrays/src/sparsematrix.jl

@@ -2172,8 +2172,10 @@ end
 _isless_fm(a, b) = b == b && ( a != a || isless(a, b) )
 _isgreater_fm(a, b) = b == b && ( a != a || isless(b, a) )
 
-findmin(A::AbstractSparseMatrixCSC{Tv,Ti}, region) where {Tv,Ti} = _findr(_isless_fm, A, region, Tv)
-findmax(A::AbstractSparseMatrixCSC{Tv,Ti}, region) where {Tv,Ti} = _findr(_isgreater_fm, A, region, Tv)
+findmin(A::AbstractSparseMatrixCSC{Tv}, region::Union{Integer,Tuple{Integer},NTuple{2,Integer}}) where {Tv} =
+ _findr(_isless_fm, A, region, Tv)
+findmax(A::AbstractSparseMatrixCSC{Tv}, region::Union{Integer,Tuple{Integer},NTuple{2,Integer}}) where {Tv} =
+ _findr(_isgreater_fm, A, region, Tv)
 findmin(A::AbstractSparseMatrixCSC) = (r=findmin(A,(1,2)); (r[1][1], r[2][1]))
 findmax(A::AbstractSparseMatrixCSC) = (r=findmax(A,(1,2)); (r[1][1], r[2][1]))
 

stdlib/SparseArrays/src/sparsevector.jl

@@ -1411,6 +1411,27 @@ end
 
 minimum(x::AbstractSparseVector) = minimum(identity, x)
 
+for (fun, comp, word) in ((:findmin, :(<), "minimum"), (:findmax, :(>), "maximum"))
+ @eval function $fun(f, x::AbstractSparseVector{T}) where {T}
+ n = length(x)
+ n > 0 || throw(ArgumentError($word * " over empty array is not allowed"))
+ nzvals = nonzeros(x)
+ m = length(nzvals)
+ m == 0 && return zero(T), firstindex(x)
+ val, index = $fun(f, nzvals)
+ m == n && return val, index
+ nzinds = nonzeroinds(x)
+ zeroval = f(zero(T))
+ $comp(val, zeroval) && return val, nzinds[index]
+ # we need to find the first zero, which could be stored or implicit
+ # we try to avoid findfirst(iszero, x)
+ sindex = findfirst(iszero, nzvals) # first stored zero, if any
+ zindex = findfirst(i -> i < nzinds[i], eachindex(nzinds)) # first non-stored zero
+ index = isnothing(sindex) ? zindex : min(sindex, zindex)
+ return zeroval, index
+ end
+end
+
 norm(x::SparseVectorUnion, p::Real=2) = norm(nonzeros(x), p)
 
 ### linalg.jl

stdlib/SparseArrays/test/sparsevector.jl

@@ -816,10 +816,14 @@ end
  @test norm(x, Inf) == 3.5
 end
 
-@testset "maximum, minimum" begin
+@testset "maximum, minimum, findmax, findmin" begin
  let x = spv_x1
  @test maximum(x) == 3.5
+ @test findmax(x) == findmax(Vector(x)) == (3.5, 6)
+ @test findmax(x -> -x, x) == findmax(-x) == (0.75, 5)
  @test minimum(x) == -0.75
+ @test findmin(x) == findmin(Vector(x)) == (-0.75, 5)
+ @test findmin(x -> -x, x) == findmin(-x) == (-3.5, 6)
  @test maximum(abs, x) == 3.5
  @test minimum(abs, x) == 0.0
  @test @inferred(minimum(t -> true, x)) === true
@@ -832,21 +836,51 @@ end
 
  let x = abs.(spv_x1)
  @test maximum(x) == 3.5
+ @test findmax(x) == findmax(Vector(x)) == (3.5, 6)
+ @test findmax(abs2, x) == findmax(abs2.(x)) == findmax(Vector(abs2.(x)))
  @test minimum(x) == 0.0
+ @test findmin(x) == findmin(Vector(x)) == (0.0, 1)
+ @test findmin(abs2, x) == findmin(abs2.(x)) == findmin(Vector(abs2.(x)))
  end
 
  let x = -abs.(spv_x1)
  @test maximum(x) == 0.0
+ @test findmax(x) == findmax(Vector(x)) == (0.0, 1)
  @test minimum(x) == -3.5
+ @test findmin(x) == findmin(Vector(x)) == (-3.5, 6)
  end
 
  let x = SparseVector(3, [1, 2, 3], [-4.5, 2.5, 3.5])
  @test maximum(x) == 3.5
+ @test findmax(x) == findmax(Vector(x)) == (3.5, 3)
  @test minimum(x) == -4.5
+ @test findmin(x) == findmin(Vector(x)) == (-4.5, 1)
  @test maximum(abs, x) == 4.5
  @test minimum(abs, x) == 2.5
  end
 
+ let x = SparseVector(3, [1, 2, 3], [4.5, 0.0, 3.5])
+ @test minimum(x) == 0.0
+ @test findmin(x) == findmin(Vector(x)) == (0.0, 2)
+ end
+
+ let x = SparseVector(3, [1, 2, 3], [-4.5, 0.0, -3.5])
+ @test maximum(x) == 0.0
+ @test findmax(x) == findmax(Vector(x)) == (0.0, 2)
+ end
+
+ for i in (2, 3)
+ let x = SparseVector(4, [1, i, 4], [4.5, 0.0, 3.5])
+ @test minimum(x) == 0.0
+ @test findmin(x) == findmin(Vector(x)) == (0.0, 2)
+ end
+
+ let x = SparseVector(4, [1, i, 4], [-4.5, 0.0, -3.5])
+ @test maximum(x) == 0.0
+ @test findmax(x) == findmax(Vector(x)) == (0.0, 2)
+ end
+ end
+
  let x = spzeros(Float64, 8)
  @test maximum(x) == 0.0
  @test minimum(x) == 0.0
@@ -861,6 +895,8 @@ end
  let x = spzeros(Float64, 0)
  @test_throws ArgumentError minimum(t -> true, x)
  @test_throws ArgumentError maximum(t -> true, x)
+ @test_throws ArgumentError findmin(x)
+ @test_throws ArgumentError findmax(x)
  end
 end