pip 无法从 requirements.txt 安装软件包

问题描述

我正在尝试使用需求文件安装 python 软件.

I am trying to install a python software using the requirements file.

>> cat requirements.txt
Cython==0.15.1
numpy==1.6.1
distribute==0.6.24
logilab-astng==0.23.1logilab-common==0.57.1
netaddr==0.7.6
numexpr==2.0.1
ply==2.5
pycallgraph==0.5.1
pyflowtools==0.3.4.1
pylint==0.25.1
tables==2.3.1
wsgiref==0.1.2

所以我创建了一个虚拟环境

So I create a virtual environment

>> mkvirtualenv parser

(parser)
>> pip freeze
distribute==0.6.24
wsgiref==0.1.2

(parser)
>> pip install -r requirements.txt

...然后我下载了包但没有安装错误:http://pastie.org/4079800

... and then I packages downloaded but not installed with errors: http://pastie.org/4079800

(parser)
>> pip freeze
distribute==0.6.24
wsgiref==0.1.2

令人惊讶的是，如果我尝试手动安装每个软件包，它们安装得很好.例如:

Surprisingly, if I try to manually install each package, they install just fine. For instance:

>> pip install numpy==1.6.1

(parser)
>> pip freeze
distribute==0.6.24
wsgiref==0.1.2
numpy==1.6.1

我迷路了.怎么回事?

PS:我正在使用 pip v1.1 和 python v2.7.2 与 virtualenv 和 virtualenvwrapper

PS: I am using pip v1.1 and python v2.7.2 with virtualenv and virtualenvwrapper

推荐答案

看起来 numexpr 包在安装时依赖于 numpy.Pip 两次通过您的要求:首先它下载所有包并运行每个包的 setup.py 以获取其元数据，然后在第二遍中安装它们.

It looks like the numexpr package has an install-time dependency on numpy. Pip makes two passes through your requirements: first it downloads all packages and runs each one's setup.py to get its metadata, and then it installs them all in a second pass.

所以，numexpr 是在它的 setup.py 中尝试从 numpy 导入，但是当 pip 第一次运行 numexpr 的 setup.py 时，它还没有安装 numpy.

So, numexpr is trying to import from numpy in its setup.py, but when pip first runs numexpr's setup.py, it has not yet installed numpy.

这也是你一个一个安装包时看不到这个错误的原因:如果你一次安装一个，numpy会在你pip install 数字表达式.