title: Fix FutureWarning related to the pandas append function
body: <p>I am getting the following FutureWarning in my Python code:</p>
  <p>FutureWarning: The frame.append method is deprecated and will be removed from pandas in a future version. Use pandas.concat instead.</p>
  <p>Right now I was using the append function, in various parts of my code, to add rows to an existing DataFrame.</p>
  <p>Example 1:</p>
  <pre><code>init_hour = pd.to_datetime('00:00:00')
  orig_hour = init_hour+timedelta(days=1)
  while init_hour &lt; orig_hour:
     row = {'Hours': init_hour.time()}
     df = df.append(row, ignore_index = True)
     init_hour = init_hour + timedelta(minutes=60)
  </code></pre>
  <p>Example 2:</p>
  <pre><code>row2 = {'date': tmp_date, 'false_negatives': fn, 'total': total}
  df2 = df2.append(row2, ignore_index = True)
  </code></pre>
  <p>How could I solve this in a simple way without modifying much of the code before the sections above?</p>