title: compare two dataframes and get nearest matching dataframe
body: <p>have two dataframes with columns</p>
  <p>df1</p>
  <pre><code>
  name    cell     marks  
  
  tom      2       21862
  
  
  </code></pre>
  <p>df2</p>
  <pre><code>
  name    cell    marks     passwd
  
  tom      2       11111      2548
  
  matt     2       158416      2483
           2       21862      26846
  
  </code></pre>
  <p>How to compare df2 with df1 and get nearest matched data frames</p>
  <p>expected_output:</p>
  <p>df2</p>
  <pre><code>
  name    cell    marks     passwd
  
  tom      2       11111      2548
           2       21862      26846
  
  </code></pre>
  <p>tried  <code>merge</code> but data is dynamic.  On one case <code>name</code> might change and in another case <code>marks</code> might change</p>