title: pandas merge by excluding certain columns from merge
body: <p>I want to merge two dataframes like:</p>
  <p><code>df1.columns = A, B, C, E, ..., D</code></p>
  <p><code>df2.columns = A, B, C, F,  ..., D</code></p>
  <p>If I merge them, it merges on all columns. Also since the number of columns is high I don't want to specify them in <code>on</code>. I prefer to exclude the columns which I don't want to be merged. How can I do that?</p>
  <pre><code>mdf = pd.merge(df1, df2, exclude D)
  </code></pre>
  <p>I expect the result be like:</p>
  <p><code>mdf.columns = A, B, C, E, F ..., D_x, D_y</code></p>