如何解决导入python包“ No module named”的问题？

Question

I am coming across a strange problem, I already installed python packages but it doesn't recognize them. please note that some packages are recognizable.

An example of importing a package

ActivePython 2.7.5.6 (ActiveState Software Inc.) based on
Python 2.7.5 (default, Sep 16 2013, 23:07:15) 
[GCC 4.2.1 (Apple Inc. build 5664)] on darwin
Type "help", "copyright", "credits" or "license" for more information.
>>> import requests
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ImportError: No module named requests

Whenever I try to install it using Pip like

sudo pip install requests

I got this message whenever I try to install the same package.

Requirement already satisfied (use --upgrade to upgrade): requests in /usr/local/lib/python2.7/site-packages

What should I do to solve this problem ?

UPDATE_1

pip --version
pip 7.1.2 from /usr/local/lib/python2.7/site-packages

Answer 1

Find where pip installs your package and add the path to

 export PYTHONPATH=<path>
 #my path was /Library/Python/2.7/site-packages

in your .bashrc or .profile file.