title: Cosine Similarity for two pyspark dataframes
body: <p>I have a PySpark DataFrame, df1, that looks like:</p>
  
  <pre><code>CustomerID  CustomerValue CustomerValue2 
  12          .17           .08
  </code></pre>
  
  <p>I have a second PySpark DataFrame, df2</p>
  
  <pre><code> CustomerID  CustomerValue CustomerValue
   15          .17           .14
   16          .40           .43
   18          .86           .09
  </code></pre>
  
  <p>I want to take the cosine similarity of the two dataframes. And have something like that</p>
  
  <pre><code> CustomerID  CustomerID   CosineCustVal CosineCustVal
   15          12           1            .90
   16          12           .45          .67
   18          12           .8           .04
  </code></pre>