与终端中的 `python` 运行位置相比，`pip` 安装库的位置在哪里？

Question

我正在尝试安装 python's scikit learn 以进行某些机器学习，并且它似乎成功地完成了（即它已经安装）。但是，当我尝试在终端的python 中实际使用它时，它给了我一个错误，如下所示。

23:39 $ sudo pip install sklearn
The directory '/Users/username/Library/Caches/pip/http' or its parent directory is not owned by the current user and the cache has been disabled. Please check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
The directory '/Users/username/Library/Caches/pip' or its parent directory is not owned by the current user and caching wheels has been disabled. check the permissions and owner of that directory. If executing pip with sudo, you may want sudo's -H flag.
Collecting sklearn
Requirement already satisfied (use --upgrade to upgrade): scikit-learn in /Library/Python/2.7/site-packages (from sklearn)
Installing collected packages: sklearn
Successfully installed sklearn-0.0
✔ /usr/bin 
23:42 $ python
Python 2.7.12rc1 (v2.7.12rc1:13912cd1e7e8, Jun 11 2016, 15:32:34) 
[GCC 4.2.1 (Apple Inc. build 5666) (dot 3)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import sklearn
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File "/Library/Python/2.7/site-packages/sklearn/__init__.py", line 57, in <module>
    from .base import clone
  File "/Library/Python/2.7/site-packages/sklearn/base.py", line 11, in <module>
    from .utils.fixes import signature
  File "/Library/Python/2.7/site-packages/sklearn/utils/__init__.py", line 11, in <module>
    from .validation import (as_float_array,
  File "/Library/Python/2.7/site-packages/sklearn/utils/validation.py", line 16, in <module>
    from ..utils.fixes import signature
  File "/Library/Python/2.7/site-packages/sklearn/utils/fixes.py", line 324, in <module>
    from scipy.sparse.linalg import lsqr as sparse_lsqr
  File "/usr/local/lib/python2.7/site-packages/scipy/sparse/linalg/__init__.py", line 112, in <module>
    from .isolve import *
  File "/usr/local/lib/python2.7/site-packages/scipy/sparse/linalg/isolve/__init__.py", line 6, in <module>
    from .iterative import *
  File "/usr/local/lib/python2.7/site-packages/scipy/sparse/linalg/isolve/iterative.py", line 7, in <module>
    from . import _iterative
ImportError: dlopen(/usr/local/lib/python2.7/site-packages/scipy/sparse/linalg/isolve/_iterative.so, 2): Symbol not found: ___addtf3
  Referenced from: /usr/local/opt/gcc/lib/gcc/6/libquadmath.0.dylib
  Expected in: /usr/lib/libSystem.B.dylib
 in /usr/local/opt/gcc/lib/gcc/6/libquadmath.0.dylib
>>> exit()
✔ /usr/bin 
23:43 $ which python
/Library/Frameworks/Python.framework/Versions/2.7/bin/python

我认为pip install <package name> 安装软件包的位置与我在终端中调用python 时实际访问它们的位置之间肯定存在一些差异。

有什么区别：

1) 通过pip install <package name> 安装软件包的位置？

与

2) 从终端调用python 时在哪里搜索包？

我将which python 的结果放在底部，因为我认为这可能有用。 另外，伙计们，我正在使用 Mac OS El Capitan 10.11.4 版。

Answer 1

这个问题与python包路径无关。这是由于未解析的符号___addtf3 是gfortran 库提供的GCC 软件浮点例程。通过正确设置DYLD_LIBRARY_PATH 环境变量解决了similar issue with a different application（与python 完全无关）。当然，您必须在系统上安装这些库，这可能是您的实际问题。