Enhance _cwt.py by introducing a configurable hop size parameter #804
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Generating a scalogram from the full output of the Continuous Wavelet Transform (CWT) entails high computational cost while providing limited performance gains in acoustic recognition models based on deep learning. Therefore, this update proposes reducing the output size during the intermediate processing stage—rather than after CWT generation—to improve computational efficiency of CWT. This pull request reflects the research findings presented in the following paper. Phan, D. T., Huynh, T. A., Pham, V. T., Tran, C. M., Mai, V. T., & Tran, N. Q. (2025). Optimal Scalogram for Computational Complexity Reduction in Acoustic Recognition Using Deep Learning. arXiv preprint arXiv:2505.13017.
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Thanks @phandangthoai. A few quick review comments inline. This change also needs tests, and it would be good to demonstrate what the gain of this is with a small benchmark.
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Hello @rgommers, |
Update _cwt.py
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Hello @rgommers,
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Thanks @phandangthoai. A few inline comments. In addtion, could you please:
- Share a benchmark script that shows the performance improvement
- Add a References section in the docstring to the paper in numpydoc format
pywt/_cwt.py
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| @@ -24,9 +24,9 @@ def next_fast_len(n): | |||
| return 2**ceil(np.log2(n)) | |||
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| def cwt(data, scales, wavelet, sampling_period=1., method='conv', axis=-1): | |||
| def cwt(data, scales, wavelet, hop_size=1, sampling_period=1., method='conv', axis=-1): | |||
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Can you please move the new keyword to the end of the signature? It's not backwards-compatible to add a new keyword in the middle. That would break calls like cwt(data, scales, wavelet, 2.5) (2.5 was the sampling period).
Also, please add it as *, hop_size=1 (the * means keyword-only).
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The examples and tests then need to be updated for that change.
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- New key word hop_size is move to the end, and defined as keyword-only.
- The examples and tests are revised accordingly and passed.
pywt/_cwt.py
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| """ | ||
| cwt(data, scales, wavelet) | ||
| cwt(data, scales, wavelet, hop_size) |
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Let's just delete this line, I don't know why it's here.
pywt/_cwt.py
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| @@ -73,7 +81,7 @@ def cwt(data, scales, wavelet, sampling_period=1., method='conv', axis=-1): | |||
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| Notes | |||
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| Size of coefficients arrays depends on the length of the input array and | |||
| Size of coefficients arrays depends on the length of the input array, the given hop_size and | |||
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Either "hop size" or use double backticks so it's typeset as code. I think I prefer the former, using natural language.
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Revised as hop size and hop_size where are needed.
Move hop_size to the end
Move hop_size to the end
Add References to the research paper.
Revise the notes
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Hello @rgommers , Thank you for your valuable feedback. I have updated the pull request in accordance with your comments. The script for generating the optimal scalogram and the script for generating the standard scalogram have been included for reference. A References section citing the relevant paper has been added to the function docstring, following the numpydoc format. Please let me know if any further revisions are required. Thank you again for your time and guidance. Best regards, |
Generating a scalogram from the full output of the Continuous Wavelet Transform (CWT) entails high computational cost while providing limited performance gains in acoustic recognition models based on deep learning. Therefore, this update proposes reducing the output size during the intermediate processing stage—rather than after CWT generation—to improve computational efficiency of CWT. This pull request reflects the research findings presented in the following paper.
Phan, D. T., Huynh, T. A., Pham, V. T., Tran, C. M., Mai, V. T., & Tran, N. Q. (2025). Optimal Scalogram for Computational Complexity Reduction in Acoustic Recognition Using Deep Learning. arXiv preprint arXiv:2505.13017.