title: How to "select distinct" across multiple data frame columns in pandas?
body: <p>I'm looking for a way to do the equivalent to the SQL </p>
  
  <pre><code>SELECT DISTINCT col1, col2 FROM dataframe_table
  </code></pre>
  
  <p>The pandas sql comparison doesn't have anything about <code>distinct</code>.</p>
  
  <p><code>.unique()</code> only works for a single column, so I suppose I could concat the columns, or put them in a list/tuple and compare that way, but this seems like something pandas should do in a more native way.  </p>
  
  <p>Am I missing something obvious, or is there no way to do this?</p>