>>> import numpy as np
>>> np.array([1, 2, 3])
array([1, 2, 3])
>>> np.array([[1, 2, 3], [4, 5, 6], [7, 8, 9]])
array([[1, 2, 3],
[4, 5, 6],
[7, 8, 9]])
>>> np.array([[[1, 2, 3], [4, 5, 6]], [[7, 8, 9], [10, 11, 12]]])
array([[[ 1, 2, 3],
[ 4, 5, 6]],
[[ 7, 8, 9],
[10, 11, 12]]])
>>> [1, 2, 3]
[1, 2, 3]
>>> np.arrange(1, 26)
array([ 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17,
18, 19, 20, 21, 22, 23, 24, 25])
>>> np.arrange(1, 26).reshape(5, 5)
array([[ 1, 2, 3, 4, 5],
[ 6, 7, 8, 9, 10],
[11, 12, 13, 14, 15],
[16, 17, 18, 19, 20],
[21, 22, 23, 24, 25]])
>>> np.arrange(1, 26).reshape(5, -1)
array([[ 1, 2, 3, 4, 5],
[ 6, 7, 8, 9, 10],
[11, 12, 13, 14, 15],
[16, 17, 18, 19, 20],
[21, 22, 23, 24, 25]])
>>> a1 = np.array([1, 2, 3], [4, 5, 6], [7, 8, 9])
>>> a2
array([[1, 2, 3],
[4, 5, 6],
[7, 8, 9]])
>>> a1[1, :]
array([4, 5, 6])
>>> a1[1, :1]
array([4])
>>> a1[1][0]
4
>>> a1[:,1]
array([2, 5, 8])
>>> a1[:,1:2]
array([[2],
[5],
[8]])