title: How to read metadata of npz file without loading it into memory
body: <p>I would like to know if it is possible to know the shape of a disk saved numpy array without loading the array into memory. This is possible with .hdf5 files, but don't know if it is possible with .npz files.
  Something like:</p>
  <pre><code>import numpy as np
  
  arr1 = np.arange(10000)
  arr2 = np.arange(10000)
  
  np.savez('tmp/my_arrays.npz', arr1 = arr1, arr2 = arr2)
  
  my_arrays = np.load('tmp/my_arrays.npz')
  
  # this loads the array into memory
  my_arrays['arr1'].shape
  
  # looking for something perhaps like
  my_arrays.arr1.shape
  
  </code></pre>