numpy.arange 等差数列

reference:
https://deepage.net/features/numpy-arange.html

>> [x for x in range(10)]
[0, 1, 2, 3, 4, 5, 6, 7, 8, 9]

>> np.array(range(10))
array([0, 1, 2, 3, 4, 5, 6, 7, 8, 9])