title: Python Pandas: If a column value equals a string, set the value of a different column cell to a certain string
body: <pre><code>import pandas as pd
  
  BabyDataSet = [('Bob', 968), ('Jessica', 155), ('Bob', 77), ('John', 578), ('Mel', 973)]
  
  df = pd.DataFrame(data=BabyDataSet, columns=['Names', 'Births'])
  </code></pre>
  <p>What I'd like to do is: If the name is &quot;Bob&quot;, then set the value of its &quot;Births&quot; to &quot;Unknown&quot; using Pandas.</p>