Save an array to a binary file in NumPy .npy format.
Parameters :  file : file or str
arr : array_like


Notes
For a description of the .npy format, see format.
Examples
>>> from tempfile import TemporaryFile
>>> outfile = TemporaryFile()
>>> x = np.arange(10)
>>> np.save(outfile, x)
>>> outfile.seek(0) # Only needed here to simulate closing & reopening file
>>> np.load(outfile)
array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])