pip无法从requirements.txt安装软件包 [英] pip fails to install packages from requirements.txt

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

...，然后我下载了但未安装但出现错误的软件包: 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，它们的安装就可以了. 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.发生了什么事?

I am lost. What is going on?

PS:我正在将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

看来numexpr软件包对numpy具有安装时依赖性. Pip进行了两次遍历您的要求:首先下载所有软件包并运行每个软件包的setup.py以获取其元数据，然后在第二遍将它们全部安装.

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.

因此，numexpr尝试从其setup.py中的numpy导入，但是当pip首次运行numexpr的setup.py时，尚未安装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.

这也是为什么在逐个安装软件包时看不到此错误的原因:如果一次安装一个软件包，则在您pip install numexpr之前，numpy将完全安装在您的环境中.

This is also why you don't see this error when you install the packages one by one: if you install them one at a time, numpy will be fully installed in your environment before you pip install numexpr.

唯一的解决方案是在运行pip install -r requirements.txt之前先安装pip install numpy-您将无法在单个命令中使用单个requirements.txt文件来完成此操作.

The only solution is to install pip install numpy before you ever run pip install -r requirements.txt -- you won't be able to do this in a single command with a single requirements.txt file.

此处的更多信息: https://github.com/pypa/pip/issues/25

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