title: Do I have to do one-hot-encoding separately for train and test dataset?
body: <p>I'm working on a classification problem and I've split my data into train and test set. </p>
  
  <p>I have few categorical columns (around 4 -6) and I am thinking of using <code>pd.get_dummies</code> to convert my categorical values to OneHotEncoding.</p>
  
  <p>My question is do I have to do OneHotEncoding separately for train and test split? If that's the case I guess I better use sklearn OneHotEncoder because it supports fit and transform methods, right?</p>