title: Pandas convert multilabeled column into separate encoded columns
body: <p>I have a Pandas series that looks like this:</p>
  <pre><code>0                                               NaN
  1                                               NaN
  2                                        red almond
  3                                       blue walnut
  4                                    RED ALMOND,BLUE WALNUT 
                             ...                     
  4051         RED_ALMOND,blue walnut,green cashew
                             ...
  4055                                            NaN
  </code></pre>
  <p>As you can see, this series contains multi-categorical data in a single column. I want to split this into separate columns such that I can encode the existence of each string (split on the comma). So ideally, something like:</p>
  <pre><code>   red almond  blue walnut green cashew
  0       0           0           0
  1       0           0           0
  2       1           0           0
  3       0           1           0
  4       1           1           0
  ...
  </code></pre>
  <p>I can't figure out how. Could someone enlighten me?</p>