title: Python: Error while installing Numpy & Pandas
body: <p>I am trying to install numpy, scipy and pandas but getting the following error:</p>
  
  <pre><code>Aleeshas-MacBook-Air:~ aleesha$ pip install numpy scipy pandas
  Requirement already satisfied (use --upgrade to upgrade): numpy in /System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python
  Requirement already satisfied (use --upgrade to upgrade): scipy in /System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python
  Collecting pandas
    Using cached pandas-0.19.1-cp27-cp27m-macosx_10_6_intel.macosx_10_9_intel.macosx_10_9_x86_64.macosx_10_10_intel.macosx_10_10_x86_64.whl
  Requirement already satisfied (use --upgrade to upgrade): pytz&gt;=2011k in /System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python (from pandas)
  Requirement already satisfied (use --upgrade to upgrade): python-dateutil in /System/Library/Frameworks/Python.framework/Versions/2.7/Extras/lib/python (from pandas)
  Installing collected packages: pandas
  Exception:
  Traceback (most recent call last):
    File "/Library/Python/2.7/site-packages/pip-8.1.2-py2.7.egg/pip/basecommand.py", line 215, in main
      status = self.run(options, args)
    File "/Library/Python/2.7/site-packages/pip-8.1.2-py2.7.egg/pip/commands/install.py", line 317, in run
      prefix=options.prefix_path,
    File "/Library/Python/2.7/site-packages/pip-8.1.2-py2.7.egg/pip/req/req_set.py", line 742, in install
      **kwargs
    File "/Library/Python/2.7/site-packages/pip-8.1.2-py2.7.egg/pip/req/req_install.py", line 831, in install
      self.move_wheel_files(self.source_dir, root=root, prefix=prefix)
    File "/Library/Python/2.7/site-packages/pip-8.1.2-py2.7.egg/pip/req/req_install.py", line 1032, in move_wheel_files
      isolated=self.isolated,
    File "/Library/Python/2.7/site-packages/pip-8.1.2-py2.7.egg/pip/wheel.py", line 346, in move_wheel_files
      clobber(source, lib_dir, True)
    File "/Library/Python/2.7/site-packages/pip-8.1.2-py2.7.egg/pip/wheel.py", line 317, in clobber
      ensure_dir(destdir)
    File "/Library/Python/2.7/site-packages/pip-8.1.2-py2.7.egg/pip/utils/__init__.py", line 83, in ensure_dir
      os.makedirs(path)
    File "/System/Library/Frameworks/Python.framework/Versions/2.7/lib/python2.7/os.py", line 157, in makedirs
      mkdir(name, mode)
  OSError: [Errno 13] Permission denied: '/Library/Python/2.7/site-packages/pandas'
  You are using pip version 8.1.2, however version 9.0.1 is available.
  You should consider upgrading via the 'pip install --upgrade pip' command.
  Aleeshas-MacBook-Air:~ aleesha$ 
  </code></pre>
  
  <p>I have Python version  - <code>Python 3.5.2</code>. Why in the first place is pip trying to install at 2.7?</p>