title: How to append a new row on pandas dataframe with single column?
body: <p>This question might seems easy but I could not find any solution for it.</p>
  
  <p>Say I have a CSV file like this without headers.</p>
  
  <pre><code>121
  334
  313
  930
  </code></pre>
  
  <p>I want to add/append new row with number <code>0</code> at the bottom like this</p>
  
  <pre><code>121
  334
  313
  930
  0
  </code></pre>
  
  <p>I tried with the following method but did not succeed.</p>
  
  <pre><code>import pandas as pd
  import os
  
  folder_path = "/home/Ling/test/"
  df = pd.read_fwf(folder_path + "test1.csv", usecols=[0], delimiter=",")
  df2 = pd.DataFrame([[0]], dtype=int)
  print df.append(df2, ignore_index=True)
  </code></pre>
  
  <p>The result</p>
  
  <pre><code>NaN 121
  NaN 334
  NaN 313
  NaN 930
  0.0 NaN
  </code></pre>
  
  <p>I am following this <a href="https://pandas.pydata.org/pandas-docs/stable/generated/pandas.DataFrame.append.html" rel="nofollow noreferrer">example</a></p>
  
  <p>I even try to change from <code>[[0]]</code> to <code>[[0,]]</code> and <code>[[,0]]</code> but did not work.
  Is there anything that I miss here in the code?</p>
  
  <p>Thank you for your help and suggestion.</p>