Python 2.7通过pip虚拟环境安装opencv

问题描述

我正在尝试通过虚拟环境（Python 2.7）中的pip安装opencv-python软件包。不幸的是，我遇到一个错误：

(venv) $ pip2 install opencv-python
DEPRECATION: Python 2.7 reached the end of its life on January 1st,2020. Please upgrade your Python as Python 2.7 is no longer maintained. pip 21.0 will drop support for Python 2.7 in January 2021. More details about Python 2 support in pip can be found at https://pip.pypa.io/en/latest/development/release-process/#python-2-support
Collecting opencv-python
  Using cached opencv-python-4.3.0.38.tar.gz (88.0 MB)
  Installing build dependencies ... done
  Getting requirements to build wheel ... error
  ERROR: Command errored out with exit status 1:
   command: /home/pc_user/.venvs/venv/bin/python /home/pc_user/.venvs/venv/lib/python2.7/site-packages/pip/_vendor/pep517/_in_process.py get_requires_for_build_wheel /tmp/tmp7q7z4L
       cwd: /tmp/pip-install-C21PKF/opencv-python
  Complete output (22 lines):
  Traceback (most recent call last):
    File "/home/pc_user/.venvs/venv/lib/python2.7/site-packages/pip/_vendor/pep517/_in_process.py",line 280,in <module>
      main()
    File "/home/pc_user/.venvs/venv/lib/python2.7/site-packages/pip/_vendor/pep517/_in_process.py",line 263,in main
      json_out['return_val'] = hook(**hook_input['kwargs'])
    File "/home/pc_user/.venvs/venv/lib/python2.7/site-packages/pip/_vendor/pep517/_in_process.py",line 114,in get_requires_for_build_wheel
      return hook(config_settings)
    File "/tmp/pip-build-env-2FzygL/overlay/lib/python2.7/site-packages/setuptools/build_meta.py",line 146,in get_requires_for_build_wheel
      return self._get_build_requires(config_settings,requirements=['wheel'])
    File "/tmp/pip-build-env-2FzygL/overlay/lib/python2.7/site-packages/setuptools/build_meta.py",line 127,in _get_build_requires
      self.run_setup()
    File "/tmp/pip-build-env-2FzygL/overlay/lib/python2.7/site-packages/setuptools/build_meta.py",line 243,in run_setup
      self).run_setup(setup_script=setup_script)
    File "/tmp/pip-build-env-2FzygL/overlay/lib/python2.7/site-packages/setuptools/build_meta.py",line 142,in run_setup
      exec(compile(code,__file__,'exec'),locals())
    File "setup.py",line 448,in <module>
      main()
    File "setup.py",line 99,in main
      % {"ext": re.escape(sysconfig.get_config_var("EXT_SUFFIX"))}
    File "/usr/lib/python2.7/re.py",line 210,in escape
      s = list(pattern)
  TypeError: 'NoneType' object is not iterable
  ----------------------------------------
ERROR: Command errored out with exit status 1: /home/pc_user/.venvs/venv/bin/python /home/pc_user/.venvs/venv/lib/python2.7/site-packages/pip/_vendor/pep517/_in_process.py get_requires_for_build_wheel /tmp/tmp7q7z4L Check the logs for full command output.

我试图创建一个新环境或通过python2 -m pip install安装，但是效果是一样的。有什么问题吗？

解决方法

opencv-python-4.3.0.38不再支持Python 2.7，自4.3.0.36起，该支持被取消，请参见this issue。

我发现的解决方法是安装opencv-python版本4.2.0.32（这是Python 2.7支持的最新版本，有关所有发行版，请参见this），如下所示：

pip2 install opencv-python==4.2.0.32