Fix trim_zeros_frames to trim zeros from the end

[yamachu]

Docs of trim_zeros_frames says Remove trailing zeros frames. But it behaves removing both front and back zero frames because of lack of np.trim_zeros 's trim option.

expected

arr = np.array(((0, 0), (1, 1), (2, 2), (0, 0)))
actual = trim_zeros_frames(arr)
# np.array(((0, 0), (1, 1), (2, 2)))

actual

arr = np.array(((0, 0), (1, 1), (2, 2), (0, 0)))
actual = trim_zeros_frames(arr)
# np.array(((0, 0), (1, 1)))

So I thought that it's better to set option trim='b'.

[codecov-io]

Codecov Report

Merging #87 into master will increase coverage by 0.13%. The diff coverage is 100%.

@@            Coverage Diff             @@
##           master      #87      +/-   ##
==========================================
+ Coverage   83.85%   83.98%   +0.13%     
==========================================
  Files          31       31              
  Lines        1697     1711      +14     
==========================================
+ Hits         1423     1437      +14     
  Misses        274      274

Impacted Files	Coverage Δ
nnmnkwii/preprocessing/generic.py	99.47% <100%> (+0.04%)	:arrow_up:

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[yamachu]

Thank you for your review.

https://github.com/r9y9/nnmnkwii/pull/87/commits/78743931b18eb24f1f843a1aaa2f9bc2e844eca3 This commit fixed commit that follow your review.

But still trimming issue remains... What do you think about my following suggestion.

• Making default value None
• If passed trim option f, b, or fb then trim_zeros_frames trims zeros frames from front, back, or front and back

These behaviors can be confirmed from these commits. https://github.com/r9y9/nnmnkwii/pull/87/commits/80a4a36026247b86b39df2125f69b8bf6b6d4a2a https://github.com/r9y9/nnmnkwii/pull/87/commits/493487b6d711905b6bec042e8f8259fcd426b7e0

Thanks.

[r9y9]

Could you put a change log in https://github.com/r9y9/nnmnkwii/blob/1649b3caba671ad203c4d599b5b8b95c168e03ac/docs/changelog.rst#v0019-2019-xx-xx? Thanks!