title: For Loop and The truth value of a Series is ambiguous
body: <p>Looked through the answers to similar queries here but still unsure. Code below produces:</p>
  
  <pre><code>     for i in range(len(df)):
              if df[0]['SubconPartNumber1'].str.isdigit() == False :
                  df['SubconPartNumber1'] = df['SubconPartNumber1'].str.replace(',', '/', regex = True)
                  df['SubconPartNumber1'] = df['SubconPartNumber1'].str.replace(r"\(.*\)-", '/', regex = True)
  ValueError: The truth value of a Series is ambiguous. Use a.empty, a.bool(), a.item(), a.any() or a.all().
  </code></pre>