title: Append row to empty pandas DataFrame
body: <p>I'm trying to create an empty pandas DataFrame with the columns <code>['ImageName','faces','ImageWidth', 'ImageHeight']</code> to which I'm trying to append a row. Let's take the following row as an example: <code>['selfie_10.png',3,200,300]</code>.</p>
  <p>So far, I've come up with the following code snippet. But either it doesn't work or it throws an error.</p>
  <pre><code>import pandas as pd
  
  columns = ['ImageName','faces','ImageWidth', 'ImageHeight']
  
  df = pd.DataFrame(columns=columns)
  
  for i in range(0,10):
      row = ['selfie_10.png',3,200,300]
      df.append(row,ignore_index=True)
   
  print(df)
  </code></pre>
  <p>The output is unfortunately an empty array.</p>
  <pre><code>In [72]:runfile('/Users/add_row.py', wdir='/Users/Desktop/faces')
  Empty DataFrame
  Columns: [ImageName, faces, ImageWidth, ImageHeight]
  Index: []
  </code></pre>
  <p>Can anybody help me?</p>