关于pip：检查我的Python是否包含所有必需的包


Check if my Python has all required packages

我有一个requirements.txt文件，其中包含我的虚拟环境所需的包列表。是否可以查明文件中提到的所有包是否都存在？如果一些包裹丢失了，如何找出丢失的包裹？

通过pkg_resourcesAPI实现这一点的方法非常简单。这些要求以SETUPTOOLS理解的格式编写。例如：

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Werkzeug>=0.6.1
Flask
Django>=1.3

示例代码：

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import pkg_resources
from pkg_resources import DistributionNotFound, VersionConflict

# dependencies can be any iterable with strings,
# e.g. file line-by-line iterator
dependencies = [
  'Werkzeug>=0.6.1',
  'Flask>=0.9',
]

# here, if a dependency is not met, a DistributionNotFound or VersionConflict
# exception is thrown.
pkg_resources.require(dependencies)
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您可以运行pip freeze查看已安装的内容，并将其与requirements.txt文件进行比较。

如果您想安装丢失的模块，可以运行pip install -r requirements.txt，然后安装丢失的模块，最后告诉您哪些模块丢失并安装了。

根据Zaur的回答，假设您确实使用了requirements.txt文件，那么您可能需要一个单元测试，可能是在tests/test_requirements.py中，以确认包的可用性。

此方法使用子测试独立地确认每个需求。这对记录所有故障很有用。

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from pathlib import Path
import unittest

import pkg_resources


class TestRequirements(unittest.TestCase):
    def test_requirements(self):
       """Recursively confirm that requirements are available."""
        # Ref: https://stackoverflow.com/a/45474387/
        requirements = (Path(__file__).parents[1] / 'requirements.in').read_text().strip().split('
')
        requirements = [r.strip() for r in requirements]
        requirements = [r for r in sorted(requirements) if r and not r.startswith('#')]
        for requirement in requirements:
            with self.subTest(requirement=requirement):
                pkg_resources.require(requirement)
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您可以通过访问系统站点包来创建virtualenv，并测试包(或其他依赖项)是否已安装。这样就不会真正安装软件包(如果您只想检查)。使用virtualenv包装器的一个例子是：

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$ cat requirements.txt
requests
simplejson

$ mkvirtualenv --system-site-packages test
Running virtualenv with interpreter /usr/bin/python2
New python executable in test/bin/python2
Also creating executable in test/bin/python
Installing setuptools, pip...done.

$ pip install -r requirements.txt
Downloading/unpacking requests (from -r requirements.txt (line 1))
  Downloading requests-2.10.0-py2.py3-none-any.whl (506kB): 506kB downloaded
Requirement already satisfied (use --upgrade to upgrade): simplejson in /usr/lib/python2.7/dist-packages (from -r requirements.txt (line 2))
Installing collected packages: requests
Successfully installed requests
Cleaning up...

$ pip install -r requirements.txt
Requirement already satisfied (use --upgrade to upgrade): requests in /home/yucer/.virtualenvs/test/lib/python2.7/site-packages (from -r requirements.txt (line 1))
Requirement already satisfied (use --upgrade to upgrade): simplejson in /usr/lib/python2.7/dist-packages (from -r requirements.txt (line 2))
Cleaning up...

$ deactivate

$ rmvirtualenv test
Removing test...

如果requirements.txt类似于：

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django
oursql
sys
notexistingmodule

然后，以下脚本将告诉您缺少哪些模块：

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#!/usr/bin/python3
fname = 'requirements.txt'
with open(fname, 'r', encoding='utf-8') as fhd:
    for line in fhd:
        try:
            exec("import" + line)
        except:
            print("[ERROR] Missing module:", line)

这将打印：

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[ERROR] Missing module: notexistingmodule
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