title: Python: how to save training datasets
body: <p>I have got training datasets, which are xtrain, ytrain, xtest and ytest. They are all numpy arrays. I want to save them together into a file, so that I can load them into workspace as done in keras for mnist.load_data: </p>
  
  <pre><code>(xtrain, ytrain), (xtest, ytest) = mnist.load_data(filepath)
  </code></pre>
  
  <p>In python, is there any way to save my training datasets into such a single file? Or is there any other appreciate methods to save them?</p>