title: How to concatenate pandas column with list values into one list?
body: <p>I have a dataframe with one of its column having a list at each index. I want to concatenate these lists into one list. I am using </p>
  
  <pre><code>ids = df.loc[0:index, 'User IDs'].values.tolist()
  </code></pre>
  
  <p>However, this results in 
  <code>['[1,2,3,4......]']</code> which is a string. Somehow each value in my list column is type <code>str</code>. I have tried converting using <code>list()</code>, <code>literal_eval()</code> but it does not work. The <code>list()</code> converts each element within a list into a string e.g. from <code>[12,13,14...]</code> to <code>['['1'',','2',','1',',','3'......]']</code>.</p>
  
  <p>How to concatenate pandas column with list values into one list? Kindly help out, I am banging my head on it for several hours. </p>