title: How to randomly split a dataset into training set, test set, and dev set in Python?
body: <p>I have a large dataset and want to randomly split the dataset into 70% train, 25% test, and 5% dev. How can I do this in Python with scikit-learn?</p>
  
  <p>I wonder if we do this using the sklearn.cross_validation.train_test_split(*arrays, **options) function like the example in the following link?</p>
  
  <p><a href="http://scikit-learn.org/stable/modules/generated/sklearn.cross_validation.train_test_split.html" rel="nofollow">http://scikit-learn.org/stable/modules/generated/sklearn.cross_validation.train_test_split.html</a></p>