title: How to combine data frames in pandas that are one below the other?
body: <pre><code>list_1  =[1, 2, 3, 4 ]
  
  def fun(list_1):
      for each value in list1:
          # perform some operation and create a new data frame(pandas) for each value in the list
          # so in total I should get 4 data frames.
  
          yield new_data_frame
  </code></pre>
  
  <p>When I call fun(list_1) I get 4 data frames one below the other:</p>
  
  <pre><code>data_frame_1
  
  data_frame_2
  
  data_frame_3
  
  data_frame_4
  </code></pre>
  
  <p>My question is, what if I need to combine the pandas data frames vertically?</p>
  
  <pre><code>data_frame_1
  +
  data_frame_2
  +
  data_frame_3
  +
  data_frame_4
  </code></pre>