title: What does np.reshape(-1) do
body: <p>I am aware of what -1 in one of the reshape dimensions does, when the other dimension is provided - say a.reshape(2,-1) ( numpy calculates the dimension for -1, based on the original array and the other dimension specified).</p>
  
  <p>But, I am not sure what a.reshape(-1) does. can some one please explain</p>