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Fix Flux.flip by providing an adjoint for Base.reverse #515

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Merged
merged 3 commits into from
Feb 25, 2020
Merged

Fix Flux.flip by providing an adjoint for Base.reverse #515

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b11399d
adjoint for Base.reverse
Feb 14, 2020
0a92f38
revert gitignore
Feb 15, 2020
8f7da4d
remove kwargs grads
Feb 17, 2020
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6 changes: 6 additions & 0 deletions src/lib/array.jl
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Expand Up @@ -63,6 +63,12 @@ end
circshift(A, shifts), Δ -> (circshift(Δ, map(-, shifts)), nothing)
end

@adjoint function reverse(x::AbstractArray, args...; kwargs...)
_reverse(t) = reverse(t, args...; kwargs...)
_nothings(t) = map(_->nothing, keys(t))
_reverse(x), Δ->(_reverse(Δ), _nothings(args)..., _nothings(kwargs)...)
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You don't need to return adjoints for the kwargs here.

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Thanks, duly noted

end

@adjoint permutedims(xs) = permutedims(xs), Δ -> (permutedims(Δ),)

@adjoint permutedims(xs::AbstractVector) = permutedims(xs), Δ -> (vec(permutedims(Δ)),)
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5 changes: 5 additions & 0 deletions test/gradcheck.jl
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Expand Up @@ -129,6 +129,11 @@ end
@test gradtest(x -> meanpool(x, pdims), x)
end

@test gradtest(x -> reverse(x), rand(17))
@test gradtest(x -> reverse(x, 8), rand(17))
@test gradtest(x -> reverse(x, 8, 13), rand(17))
@test gradtest(x -> reverse(x, dims=2), rand(17, 42))

@test gradtest(x -> permutedims(x), rand(2))
@test gradtest(x -> permutedims(x), rand(2,3))
@test gradtest(x -> permutedims(x, [3,1,2]), rand(4,5,6))
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