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Implement efficent methods for any/all #32

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Implement efficent methods for any/all #32

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acfe9dd
Implement efficent methods for `any`/`all`
goretkin Apr 21, 2020
fadf55b
Handle predicate variant of any/all and `missing`
goretkin Apr 22, 2020
cb77668
julia 0.7/1.0 ambiguity patch for `all`
johnnychen94 Apr 23, 2020
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10 changes: 10 additions & 0 deletions src/PaddedViews.jl
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Original file line number Diff line number Diff line change
Expand Up @@ -309,4 +309,14 @@ function Base.showarg(io::IO, A::PaddedView, toplevel)
toplevel && print(io, " with eltype ", eltype(A))
end

# The fallbacks work, but this is more efficient
# TODO use use short-circuit evaluation,
Base.any(f::Function, A::PaddedView) = f(A.fillvalue) | any(f, parent(A))
Base.all(f::Function, A::PaddedView) = f(A.fillvalue) & all(f, parent(A))
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it doesn't support dims keyword

julia> pa = PaddedView(false, a, (1:2, 1:2));

julia> any(pa; dims=1)
ERROR: ArgumentError: No method is implemented for reducing index range of type typeof(i). Please implement
reduced_index for this index type or report this as an issue.

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Base.all(A::PaddedView) = all(identity, A)

is still needed, otherwise it calls the fallback.

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julia> a = fill(true, 2, 2)
2×2 Array{Bool,2}:
 1  1
 1  1

julia> A = PaddedView(false, a, axes(a))
2×2 PaddedView(false, ::Array{Bool,2}, (Base.OneTo(2), Base.OneTo(2))) with eltype Bool:
 1  1
 1  1

julia> all(identity, A)
false

julia> all(identity, collect(A))
true

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@goretkin, I pointed this problem in JuliaLang/julia#35563 (comment).

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Similarly, there is a problem with cropping.
I have a sense of foreboding about the combination of those and dims.:fearful:

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@kimikage Yeah, I am not sure it is worthwhile to implement anything clever for dims. The required reasoning would be substantially more complex, and I can imagine it being slower for many cases where there isn't that much padding.

Not sure what problem with cropping you mean.

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julia> a = Bool[0 0; 1 1]
2×2 Array{Bool,2}:
 0  0
 1  1

julia> A = PaddedView(false, a, (1,3))
1×3 PaddedView(false, ::Array{Bool,2}, (Base.OneTo(1), Base.OneTo(3))) with eltype Bool:
 0  0  0

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Thanks for the example! Yeah, that would also need to be handled for sure.

if v"0.7" <= VERSION < v"1.1"
# ambiguity patch
# https://github.com/JuliaLang/julia/pull/30904
Base.all(::typeof(isinteger), ::PaddedView{<:Integer}) = true
end

end # module
28 changes: 28 additions & 0 deletions test/runtests.jl
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Expand Up @@ -251,3 +251,31 @@ end
@test Ap[axes(A)...] == A
end
end

@testset "specializations" begin
@testset "trivalent logic" begin
for (p, v) in Iterators.product(ntuple(_->(true, false, missing), 2)...)
a = fill(v, (1, 1))
pa = PaddedView(p, a, (1:2, 1:2))
mpa = collect(pa)
# ensure specializations are equivalent to fallbacks
for f in (any, all)
@test isequal(f(pa), f(mpa))
end
end
end
@testset "with predicates" begin
for (p, v) in Iterators.product(ntuple(_->(0, 1), 2)...)
a = fill(v, (1, 1))
pa = PaddedView(p, a, (1:2, 1:2))
mpa = collect(pa)
# ensure specializations are equivalent to fallbacks
fp = ==(0)
for f in (any, all)
v1 = f(fp, pa)
v2 = f(fp, mpa)
@test isequal(v1, v2)
end
end
end
end