title: Python create new column from dictionary keys
body: <p>I am trying to learn using Python for Data Science and got stuck with the following problem.</p>
  
  <p>Suppose that we have a data frame of the form</p>
  
  <p><a href="https://i.stack.imgur.com/GZoUS.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/GZoUS.png" alt="enter image description here"></a></p>
  
  <p>and dictionary of the form</p>
  
  <pre><code>    Regions = {“Central Asia”: [“Afghanistan”], 
  “Europe”: [“Albania”, “Andorra”], 
  “Africa”: [“Algeria”], 
  “America”: [“American Samoa”]}
  </code></pre>
  
  <p>I would like to create a new column in the data frame with keys from this dictionary being the entries, like this:</p>
  
  <p><a href="https://i.stack.imgur.com/oZ4ge.png" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/oZ4ge.png" alt="enter image description here"></a></p>
  
  <p>Is there a good way to do this in Python? </p>
  
  <p>Thanks for your help!!</p>