Cannot import pandas after pip install pandas
Question: I run the following command to install `pandas` via `pip`:

    
    
    sudo pip install pandas --upgrade
    

which outputs

    
    
    Requirement already up-to-date: pandas in /opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages
    Requirement already up-to-date: numpy>=1.7.0 in /opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages (from pandas)
    Requirement already up-to-date: python-dateutil>=2 in /opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages (from pandas)
    Requirement already up-to-date: pytz>=2011k in /opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages (from pandas)
    Requirement already up-to-date: six>=1.5 in /opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages (from python-dateutil>=2->pandas)
    

However, when I use `python3` in the command line, I cannot import `pandas`:

    
    
    $ python3
    >>> import pandas
    >>> Traceback (most recent call last):
      File "<stdin>", line 1, in <module>
    ImportError: No module named 'pandas'
    

It appears that this is in the correct location, as

    
    
    which python3 
    

is in the following location:

    
    
    /opt/local/bin/python3
    

Executing within python3

    
    
     >>> import sys
     >>> print(sys.version)
    

outputs

    
    
    '3.4.5 (default, Jun 27 2016, 04:57:21) \n[GCC 4.2.1 Compatible Apple LLVM 7.0.2 (clang-700.1.81)]'
    

Why can't I import pandas?

EDIT: I'm using pip version pip3:

    
    
    pip --version
    

outputs

    
    
    pip 8.1.2 from /opt/local/Library/Frameworks/Python.framework/Versions/3.4/lib/python3.4/site-packages (python 3.4)
    


Answer: Looks like your OS uses pip2 by default. This could be checked by typing:

    
    
    $ pip --version
    pip 8.1.2 from /usr/local/lib/python2.7/dist-packages (python 2.7)
    

Try to use `pip3` command like that:

    
    
    sudo pip3 install pandas --upgrade
    

