title: Keep other variables when executing get_dummies in Pandas
body: <p>I have a DataFrame with an ID variable and another categorical variable. I want to create dummy variables out of the categorical variable with get_dummies.</p>
  
  <pre><code>dum = pd.get_dummies(df)
  </code></pre>
  
  <p>However, this makes the ID variable disappear. And I need this ID variable later on to merge to other data sets. </p>
  
  <p>Is there a way to keep other variables. In the documentation of get_dummies I could not find anything. Thanks!</p>