title: Dummy Variables in Python SKLearn Logistic Regression
body: <p>I am using logisitic regression in SKLearn to classify data into one of 5 classes. To train the data I have a matrix of observations <code>Y</code> and a matrix of features <code>X</code>.</p>
  
  <p>Sometimes it is the case that my matrix <code>Y</code> will have no category 3 say. In this case when I call the <code>predict_proba(X)</code> method I would like to have a list of 5 probabilities where the 3rd entry is 0 (as there are no category 3 observations). Instead this probability is simply omitted and a list of 4 probabilities is returned.</p>
  
  <p>How can I change the logistic regression object to do this?</p>