title: pandas how to replace only empty list data?
body: <p>my dataframe look like this:</p>
  <pre><code>   variations_list1          variations_list2
      [&quot;yellow&quot;,&quot;ornage&quot;]          []
      [&quot;xl&quot;,&quot;xxl&quot;]                 []
      [&quot;Burger&quot;,&quot;pizza&quot;]         [&quot;$25&quot;,&quot;$30&quot;]
  </code></pre>
  <p>expected dataframe:</p>
  <pre><code> variations_list1          variations_list2
      [&quot;yellow&quot;,&quot;ornage&quot;]         [&quot;yellow&quot;,&quot;ornage&quot;] #filling emty list with current row data
      [&quot;xl&quot;,&quot;xxl&quot;]                [&quot;xl&quot;,&quot;xxl&quot;]
      [&quot;Burger&quot;,&quot;pizza&quot;]         [&quot;$25&quot;,&quot;$30&quot;]
  </code></pre>