ENH: add iswtn (n-dimensional inverse SWT) #256
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Current coverage is 86.96% (diff: 100%)@@ master #256 diff @@
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Also from the perspective of symmetry with other functions ( Needs a rebase. |
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| assert_raises(ValueError, pywt.swt2, x, 'haar', level=1) | |||
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| @dec.slow | |||
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Can we have one test not marked as slow for iswt2 and iswtn? The default for test() is not to run slow tests, so easy to be developing for some time without running any tests for these functions otherwise.
These do not require a slow decorator, but only test a single wavelet type.
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This has now been rebased. I added versions of the 2D and nD tests that just call the existing tests for a single wavelet type so that they are very fast. Most of the other changes in the tests file are minor simplifications: use the kind='discrete' keyword when generating the lists of wavelets to test to avoid the need for type checking later. |
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Test failures are unrelated to this PR, due to the new |
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Allright, all green after restarting the build now that coverage 4.3.1 is on PyPI. |
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Merged, thanks @grlee77! |
In release 0.5.1 there is
swtnfor an n-dimensional forward SWT with flexible choice of axes to transform. This PR provides the corresponding inverse operation,iswtn.The redundancy of the SWT grows quickly as the number of dimensions (and transform levels) increases, but I think it is still worth having this generalized implementation available.
This logic here may be a bit hard to follow with all the slice objects, use of
itertools.productfor nested loops etc. However, it is a direct extension of the approach used iniswt2(i.e. combining all possible combinations of odd/even shifts ofidwtnalong the transformed axes). The tests are pretty thorough, so I am fairly confident that the implementation is correct.This makes
iswt2a bit redundant, but I think keeping a simpler 2D example around serves as a useful reference in understanding the approach behindiswtn.