Array a containing one zero element and a.any() in function hough_line_peaks in file skimage/transform/hough_transform.py

[uzgithub]

Description

The function hough_line_peaks in the file skimage/transform/hough_transform.py contains the following logic in line 64f

if a.any():
return (h, angles[a], dists[d])
else:
return (h, np.array([]), np.array([]))

In the edge case of a being an array with just one element, and that element being equal to 0, according to the logic given above, an empty array is returned because of the use of a.any(), instead of angles[0].

Version information

3.6.3 (default, May 31 2019, 13:05:43)
[GCC 4.8.5 20150623 (Red Hat 4.8.5-36)]
Linux-3.10.0-957.27.2.el7.x86_64-x86_64-with-centos-7.6.1810-Core
scikit-image version: 0.15.0
numpy version: 1.17.1

[hmaarrfk]

It seems like your reproducing example is almost complete.

Could you please provide all the code start to finish? that will be half way to adding the test we need to the library to ensure this bug doesn't happen again!

[hmaarrfk]

Also, if you would like to help address this issue, we will gladly review your PR! Contributions are welcome!

[grlee77]

a concrete example of this issue was more recently given in #6187 (comment)