title: How to clean iPython environment so I can start over with Jupyter and Python 3.x?
body: <p>Over the past couple years I've <code>pip installed</code> lots of things without knowing what I was doing. All of a sudden, I am getting this error when I run a snippet in a Python 2.7 Jupyter Notebook:</p>
  
  <pre><code>ImportError: No module named matplotlib
  </code></pre>
  
  <p>When I run this in Terminal: <a href="https://stackoverflow.com/a/33175893/896802"><code>which -a python python 3</code></a>... I get:</p>
  
  <pre><code>Sams-MacBook-Pro-2:~ sambrand$ which -a python python3
  //anaconda/bin/python
  /usr/local/bin/python
  /usr/bin/python
  /usr/local/bin/python
  </code></pre>
  
  <p>I <em>think</em> this is showing that I have Python in a few places, which might explain why my standard libraries (eg. matplotlib) aren't being found in the Python environment that I want to use.</p>
  
  <p><strong>My ideal result:</strong> </p>
  
  <p>Ultimately, I just want to clean up my environment and start from scratch so that I can use Keras, Tensorflow, and all Anaconda packages with Python 3 as my default when I open a Jupyter Notebook. </p>
  
  <p>Additionally, I'd like any subsequent <code>pip install</code> from the terminal to update what I'm using in Jupyter.</p>
  
  <p>From what I gather, <a href="https://twitter.com/amuellerml/status/932637063748444160" rel="noreferrer">this kind of bewilderment about Python environment</a> is a fairly common issue, so I hope this post proves helpful.</p>