已安装numpy仍遇lap安装报错：ModuleNotFoundError问题求助

问题重现 #

• 创建Python3虚拟环境：python3 -m venv .venv
• 激活虚拟环境：source .venv/bin/activate
• 安装numpy模块：python3 -m pip install numpy
• 尝试安装lap模块：python3 -m pip install lap，此时报错ModuleNotFoundError: No module named 'numpy'及ImportError: lap requires numpy, please "pip install numpy"

更新测试 #

使用新虚拟环境.venv2重复操作，直接安装lap时仍出现相同错误，具体报错信息：

vbulash@vbulash-notebook:~/VSCode/recognition$ python3 -m venv .venv2
vbulash@vbulash-notebook:~/VSCode/recognition$ source .venv2/bin/activate
(.venv2) vbulash@vbulash-notebook:~/VSCode/recognition$ python3 -m pip install lap
Collecting lap
  Using cached lap-0.4.0.tar.gz (1.5 MB)
  Installing build dependencies ... done
  Getting requirements to build wheel ... done
  Installing backend dependencies ... done
  Preparing metadata (pyproject.toml) ... error
  error: subprocess-exited-with-error
  
  × Preparing metadata (pyproject.toml) did not run successfully.
  │ exit code: 1
  ╰─> [23 lines of output]
      <string>:4: DeprecationWarning: pkg_resources is deprecated as an API. See https://setuptools.pypa.io/en/latest/pkg_resources.html
      Partial import of lap during the build process.
      Traceback (most recent call last):
        File "<string>", line 127, in get_numpy_status
      ModuleNotFoundError: No module named 'numpy'
      Traceback (most recent call last):
        File "/home/vbulash/VSCode/recognition/.venv2/lib/python3.12/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 353, in <module>
          main()
        File "/home/vbulash/VSCode/recognition/.venv2/lib/python3.12/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 335, in main
          json_out['return_val'] = hook(**hook_input['kwargs'])
                                   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        File "/home/vbulash/VSCode/recognition/.venv2/lib/python3.12/site-packages/pip/_vendor/pyproject_hooks/_in_process/_in_process.py", line 149, in prepare_metadata_for_build_wheel
          return hook(metadata_directory, config_settings)
                 ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
        File "/tmp/pip-build-env-1zmi7bid/overlay/lib/python3.12/site-packages/setuptools/build_meta.py", line 366, in prepare_metadata_for_build_wheel
          self.run_setup()
        File "/tmp/pip-build-env-1zmi7bid/overlay/lib/python3.12/site-packages/setuptools/build_meta.py", line 487, in run_setup
          super().run_setup(setup_script=setup_script)
        File "/tmp/pip-build-env-1zmi7bid/overlay/lib/python3.12/site-packages/setuptools/build_meta.py", line 311, in run_setup
          exec(code, locals())
        File "<string>", line 236, in <module>
        File "<string>", line 220, in setup_package
      ImportError: lap requires numpy, please "pip install numpy".
      [end of output]
  
  note: This error originates from a subprocess, and is likely not a problem with pip.
error: metadata-generation-failed

× Encountered error while generating package metadata.
╰─&gt; See above for output.

原因分析 #

lap包在构建元数据（metadata）阶段就需要依赖numpy，但pip默认启用构建隔离机制，会创建临时的隔离环境来构建包，该环境不会包含你已在虚拟环境中安装的numpy，因此即使提前安装了numpy，构建lap时仍会提示找不到依赖。

解决方案 #

关闭pip的构建隔离，让构建过程直接使用当前虚拟环境的依赖：

1. 激活虚拟环境后，先安装numpy：

   python3 -m pip install numpy
   

2. 接着使用--no-build-isolation参数安装lap：

   python3 -m pip install lap --no-build-isolation
   

内容的提问来源于stack exchange，提问作者vbulash