find_peaks_cwt has undocumented behavior when window_size is None and wavelet is ricker

From the documentation for find_peaks_cwt (window_size):

Size of window to use to calculate noise floor. Default is cwt.shape[1] / 20.

However, when window_size is None and wavelet = ricker (default for find_peaks_cwt) this will also trigger special case handing in scipy.signal.wavelets.cwt:

 if wavelet == ricker and window_size is None:
     ceil = np.ceil(N)
     if ceil != N:
         N = int(N)

which affects the output with my supplied input: input.txt. So, in the end the result from find_peaks_cwt differs between when window_size is None and cwt.shape[1] / 20.

Reproducing code example:

>>> import json
>>> import numpy as np
>>> from scipy import signal
>>> vector = np.array(json.load(open('input.txt')))  # Attached file
>>> widths = np.linspace(1, 265)
>>> signal.find_peaks_cwt(vector, widths)
array([  22,  436,  868, 1299, 1732, 2164, 2596, 3028, 3459, 3892, 4324, 4756, 5189, 5620, 6052, 6484, 6916, 7349, 7780, 8212, 8625])
# window_size gets computed in _filter_ridge_lines to 433
>>> window_size = int(np.ceil(len(vector) / 20))
# Now, I supply this computed window_size:
>>> signal.find_peaks_cwt(vector, widths, window_size=window_size)
array([  23,  436,  868, 1300, 1732, 2164, 2596, 3028, 3460, 3892, 4325, 4757, 5189, 5621, 6053, 6485, 6917, 7349, 7781, 8213, 8626])

Scipy/Numpy/Python version information:

1.5.2 1.17.5 sys.version_info(major=3, minor=8, micro=5, releaselevel='final', serial=0)

[ilayn]

Today I am exceptionally stupid. Happened a few times with other PRs too. Sorry for that. I’ll fill the bathtub with coffee.

[tylerjereddy]

For the 1.6.0 release, I believe we may be dropping that NumPy version range, so just deleting the shim might be ok.