OpenCV 3.4.4 Python binding

[h6197627]

In newly released OpenCV 3.4.4 python bindings installation process was changed. Now it creates new folder /usr/local/python with python binding stuff. To make it visible in python user should run setup script from this folder. However after installation I am getting error:

>>> import cv2
['/usr/local/lib/python3.6/dist-packages/opencv-3.4.4-py3.6.egg/cv2/../../python/cv2/python-3.6', '', '/usr/lib/python36.zip', '/usr/lib/python3.6', '/usr/lib/python3.6/lib-dynload', '/usr/local/lib/python3.6/dist-packages', '/usr/local/lib/python3.6/dist-packages/scipy-1.1.0-py3.6-linux-x86_64.egg', '/usr/local/lib/python3.6/dist-packages/protobuf-3.6.1-py3.6-linux-x86_64.egg', '/usr/local/lib/python3.6/dist-packages/pycuda-2018.1.1-py3.6-linux-x86_64.egg', '/usr/local/lib/python3.6/dist-packages/Mako-1.0.7-py3.6.egg', '/usr/local/lib/python3.6/dist-packages/appdirs-1.4.3-py3.6.egg', '/usr/local/lib/python3.6/dist-packages/decorator-4.3.0-py3.6.egg', '/usr/local/lib/python3.6/dist-packages/pytest-3.9.3-py3.6.egg', '/usr/local/lib/python3.6/dist-packages/pytools-2018.5.2-py3.6.egg', '/usr/local/lib/python3.6/dist-packages/MarkupSafe-1.0-py3.6-linux-x86_64.egg', '/usr/local/lib/python3.6/dist-packages/py-1.7.0-py3.6.egg', '/usr/local/lib/python3.6/dist-packages/pluggy-0.8.0-py3.6.egg', '/usr/local/lib/python3.6/dist-packages/more_itertools-4.3.0-py3.6.egg', '/usr/local/lib/python3.6/dist-packages/attrs-18.2.0-py3.6.egg', '/usr/local/lib/python3.6/dist-packages/atomicwrites-1.2.1-py3.6.egg', '/usr/local/lib/python3.6/dist-packages/numpy-1.15.4-py3.6-linux-x86_64.egg', '/usr/local/lib/python3.6/dist-packages/opencv-3.4.4-py3.6.egg', '/usr/lib/python3/dist-packages', '/usr/lib/python3.6/dist-packages']
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/usr/local/lib/python3.6/dist-packages/opencv-3.4.4-py3.6.egg/cv2/__init__.py", line 89, in <module>
    bootstrap()
  File "/usr/local/lib/python3.6/dist-packages/opencv-3.4.4-py3.6.egg/cv2/__init__.py", line 79, in bootstrap
    import cv2
  File "/usr/local/lib/python3.6/dist-packages/opencv-3.4.4-py3.6.egg/cv2/__init__.py", line 89, in <module>
    bootstrap()
  File "/usr/local/lib/python3.6/dist-packages/opencv-3.4.4-py3.6.egg/cv2/__init__.py", line 23, in bootstrap
    raise ImportError('ERROR: recursion is detected during loading of "cv2" binary extensions. Check OpenCV installation.')
ImportError: ERROR: recursion is detected during loading of "cv2" binary extensions. Check OpenCV installation.

Also I have another question - is it possible to configure CMake to use only Ubuntu OS dedicated folders for python binding installation (/usr/local/lib/pythonX.X/dist-packages) without creating new non-standard directories (/usr/local/python)?

System information (version)

• OpenCV => 3.4.4
• Operating System / Platform => Ubuntu 18.04
• Compiler => GCC

Steps to reproduce

1. build OpenCV with python bindings
2. cd /usr/local/python
3. sudo python3 setup.py install
4. python3

5. import cv2

[alalek]

There are these options:

1. Don't install this loader package (it is mostly for standalone distributions): python: bindings loader package #12977 (comment)

Old behavior can restored via these CMake variables:

• OPENCV_SKIP_PYTHON_LOADER=ON
• OPENCV_PYTHON3_INSTALL_PATH=...site/dist-packages location... (not required since python: update install paths #13254)

2. setup.py is not complete for now and its usage is very limited (it is a bit tricky to install native binaries with their dependencies in Python). Try to install this loader in develop mode instead:

python3 setup.py develop
or
pip install -e .

3. There is bug with paths:

opencv-3.4.4-py3.6.egg/cv2/../../python/cv2/python-3.6

should be

opencv-3.4.4-py3.6.egg/cv2/python-3.6

[h6197627]

Thanks @alalek for helping! I will use old approach for now.

[wangqr]

The printed path in the archlinux package includes '/build/opencv/src/build/lib/python3', which seems to be the building directory. Is this the expected behavior with the new loader?

[sergiomb2]

huf ! , you need do another release , install pyhton path are wrong , and just after a complete build we notice it, I spent one day to find it .

[tomrunia]

I ran into the same error with OpenCV 4.0.0 on MacOS with Python 3.7.
This fixed it for me: python3 setup.py develop

[sergiomb2]

Old behavior can restored via these CMake variables:

OPENCV_SKIP_PYTHON_LOADER=ON

2 questions

• Why this new behavior is default instead old behavior ?
• What is the benefits of this new behavior ? ( which in Fedora packages seems that install python bindings in a not standard folder)

[edrozenberg]

Ran into this also. Was not fun, and also my package created using make install DESTDIR now requires an additional non-standard, non-discoverable manual step to get the bindings set up after the package is installed on each target.