上面的大多数其他答案都不能与当前版本的pip API一起使用。下面是使用pip当前版本(撰写本文时为6.0.8，在7.1.2中也有效)的正确*方法。您可以使用pip -V检查您的版本。

from pip.req import parse_requirements
from pip.download import PipSession

install_reqs = parse_requirements(<requirements_path>, session=PipSession())

reqs = [str(ir.req) for ir in install_reqs]

setup(
    ...
    install_requires=reqs
    ....
)

正确，因为这是当前pip使用parse_requirements的方式。这仍然可能不是最好的方法，因为正如上面的帖子所说，pip并没有真正维护API。

我是这样做的:

import re

def requirements(filename):
    with open(filename) as f:
        ll = f.read().splitlines()
    d = {}
    for l in ll:
        k, v = re.split(r'==|>=', l)
        d[k] = v
    return d

def packageInfo():
    try:
        from pip._internal.operations import freeze
    except ImportError:
        from pip.operations import freeze

    d = {}
    for kv in freeze.freeze():
        k, v = re.split(r'==|>=', kv)
        d[k] = v
    return d

req = getpackver('requirements.txt')
pkginfo = packageInfo()

for k, v in req.items():
    print(f'{k:<16}: {v:<6} -> {pkginfo[k]}')

以下接口在pip 10中已弃用:

from pip.req import parse_requirements
from pip.download import PipSession

所以我把它转换成简单的文本解析:

with open('requirements.txt', 'r') as f:
    install_reqs = [
        s for s in [
            line.split('#', 1)[0].strip(' \t\n') for line in f
        ] if s != ''
    ]

下面是一个完整的hack(用pip 9.0.1测试)，基于Romain的回答，解析requirements.txt，并根据当前的环境标记进行过滤:

from pip.req import parse_requirements

requirements = []
for r in parse_requirements('requirements.txt', session='hack'):
    # check markers, such as
    #
    #     rope_py3k    ; python_version >= '3.0'
    #
    if r.match_markers():
        requirements.append(str(r.req))

print(requirements)

另一个可能的解决方案……

def gather_requirements(top_path=None):
    """Captures requirements from repo.

    Expected file format is: requirements[-_]<optional-extras>.txt

    For example:

        pip install -e .[foo]

    Would require:

        requirements-foo.txt

        or

        requirements_foo.txt

    """
    from pip.download import PipSession
    from pip.req import parse_requirements
    import re

    session = PipSession()
    top_path = top_path or os.path.realpath(os.getcwd())
    extras = {}
    for filepath in tree(top_path):
        filename = os.path.basename(filepath)
        basename, ext = os.path.splitext(filename)
        if ext == '.txt' and basename.startswith('requirements'):
            if filename == 'requirements.txt':
                extra_name = 'requirements'
            else:
                _, extra_name = re.split(r'[-_]', basename, 1)
            if extra_name:
                reqs = [str(ir.req) for ir in parse_requirements(filepath, session=session)]
                extras.setdefault(extra_name, []).extend(reqs)
    all_reqs = set()
    for key, values in extras.items():
        all_reqs.update(values)
    extras['all'] = list(all_reqs)
    return extras

然后使用…

reqs = gather_requirements()
install_reqs = reqs.pop('requirements', [])
test_reqs = reqs.pop('test', [])
...
setup(
    ...
    'install_requires': install_reqs,
    'test_requires': test_reqs,
    'extras_require': reqs,
    ...
)

交叉张贴我从这个SO问题的答案，另一个简单的，pip版本证明解决方案。

try:  # for pip >= 10
    from pip._internal.req import parse_requirements
    from pip._internal.download import PipSession
except ImportError:  # for pip <= 9.0.3
    from pip.req import parse_requirements
    from pip.download import PipSession

requirements = parse_requirements(os.path.join(os.path.dirname(__file__), 'requirements.txt'), session=PipSession())

if __name__ == '__main__':
    setup(
        ...
        install_requires=[str(requirement.req) for requirement in requirements],
        ...
    )

然后把所有的需求放在项目根目录下的requirements.txt下。