Add LPNormPool #2166
Add LPNormPool #2166
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src/layers/conv.jl
Outdated
| LPNormPool(window::NTuple, p::Number; pad=0, stride=window) | ||
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| Lp norm pooling layer, calculating p-norm distance for each window, | ||
| also known as LPPool in pytorch. |
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One vote to call this NormPool. One reason besides brevity is that it'll be hard to remember whether the p is uppercase -- you write "Lp norm" just below, which I think is standard (lower-case, ideally subscript) and suggests LpNormPool.
I think it's good to mention pytorch's name, to be searchable. But IMO this should be somewhere down next to "See also", not in the first sentence.
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I still have no idea about struct name. Hope for more discussion :)
About pytorch metion, The reason I add this here is to make user find it is identical to LPPool in pytorch more quickly. I think it's nice to append LPPool in "See also". I'll add it in new commit.
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Looking at the PyTorch implementation, there does appear to be a meaningful difference from taking the norm of every window. Lp-pooling lacks the absolute value used in the p-norm, so negative inputs remain negative at odd powers. Unless we want to deviate from PyTorch, I think that lends credence to not calling this "NormPool".
>>> x = torch.tensor([-1, -2, -3, 1, 2, 3]).reshape(1, 1, -1)
>>> torch.nn.functional.lp_pool1d(x, 1, 1)
tensor([[[-1., -2., -3., 1., 2., 3.]]])There was a problem hiding this comment.
Oh that's very different. What does it do for power 3, and for 1.5?
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>>> torch.nn.functional.lp_pool1d(x, 3, 1)
tensor([[[nan, nan, nan, 1., 2., 3.]]])
>>> torch.nn.functional.lp_pool1d(x, 1.5, 1)
tensor([[[nan, nan, nan, 1., 2., 3.]]])Compare:
>>> torch.linalg.norm(torch.tensor([-1.]), ord=1)
tensor(1.)
>>> torch.linalg.norm(torch.tensor([-1.]), ord=3)
tensor(1.)
>>> torch.linalg.norm(torch.tensor([-1.]), ord=1.5)
tensor(1.)There was a problem hiding this comment.
Note that there are other choices which would agree with this one when x is positive:
- Could take
norm(xs, p), as theabsdoes nothing except when at present you'll get an error. The NNlib function (and the pytorch one) do allow negative x when p=1, and this would change the answer.- Could take
y = sum(x -> sign(x) * abs(x)^p, xs); sign(y) * abs(x)^(1/p).
Oh, yes. I will update for this more carefully.
Could do.
iseven(2.0), iseven(2.01)seems to behave well.
And this.
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My question is whether I can use try-catch to catch DomainError thrown by function ^(x, y) after skimming After skimming https://fluxml.ai/Zygote.jl/stable/limitations/#Try-catch-statements-1. function ^(x, y) allows even exp and performs well in case of special exp.
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I don't think try-catch is the way to go. This function should decide what it accepts, and check its input. Note for example that CUDA doesn't always follow Base in these things:
julia> cu([-1 0 1]) .^ 2.1f0
1×3 CuArray{Float32, 2, CUDA.Mem.DeviceBuffer}:
NaN 0.0 1.0
julia> [-1 0 1] .^ 2.1f0
ERROR: DomainError with -1.0:There was a problem hiding this comment.
The existing check is fine, no try-catch required. The short-circuiting I was referring to was inserting a iseven(p) && before the any check for negative elements.
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I don't think try-catch is the way to go. This function should decide what it accepts, and check its input.
Make sense! I learn a lot.
skyleaworlder
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… in Flux, rather than 'function ^(x, y)' in Base.Math
PR Checklist
About #1431 Pooling Layers |
LPPool1d,LPPool2d.