title: How do you create a master data frame from appending many data frames together?
body: <p>I am attempting to loop over many pages of data, with the same format, to acquire one large master data frame of all the data appended together. When I run this code however, the master_df comes up empty, as if the new_df isn't being appended to the master. Any thoughts? Thanks in advance!</p>
  
  <pre><code>alphabet_list = ['a','b','c','d','e','f']
  
  master_df = pd.DataFrame([])
  
  for letter in alphabet_list:
  
      player_df = pd.read_html('https://www.nfl.com/players/active/{}'.format(letter))
  
      new_df = player_df[0]
  
      master_df = new_df.append(new_df)
  </code></pre>