https://github.com/Createdd/Writing/blob/master/2020/articles/NumpyShapesAndSlices.md

NumpyShapesAndSlices.py

import numpy as np

one_dim = np.ones(shape=(5), dtype=np.int)

# print(one_dim)
# [1 1 1 1 1]

two_dim = np.ones(shape=(5, 2), dtype=np.int)

# print(two_dim)
# [[1 1]
#  [1 1]
#  [1 1]
#  [1 1]
#  [1 1]]


three_dim = np.ones(shape=(3, 2, 1), dtype=np.int)

# print(three_dim)
# [[[1]
#   [1]]
#  [[1]
#   [1]]
#  [[1]
#   [1]]]

a_range = np.arange(5)

# print(a_range)
# [0 1 2 3 4]

a_sliced_range = np.arange(2, 5)

# print(a_range)
# [2 3 4]

a_range = np.arange(5)

# print(a_range)
# print(a_range[2])
# [0 1 2 3 4]
# 2

a_range = np.arange(5)

# print(a_range)
# print(a_range[2:4])
# [0 1 2 3 4]
# [2 3]

two_dim = np.linspace((0, 5, 10), (4, 9, 14), 5)

# print(two_dim)
# # [[ 0.  5. 10.]
# #  [ 1.  6. 11.]
# #  [ 2.  7. 12.]
# #  [ 3.  8. 13.]
# #  [ 4.  9. 14.]]
# print(two_dim[2:4])
# # [[ 2.  7. 12.]
# #  [ 3.  8. 13.]]
# print(two_dim[2, 2])
# # 12.
# print(two_dim[:, 2])
# # [10. 11. 12. 13. 14.]
# print(two_dim[2, :])
# # [ 2.  7. 12.]

a_range = np.arange(27)
three_dim = a_range.reshape(3, 3, 3)
# print(three_dim)
# [[[ 0  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 26]]]
# print(three_dim[0, 1, 2])
# 5
# print(three_dim[0, 1])
# [3 4 5]
# print(three_dim[0][1])
# [3 4 5]
# print(three_dim[:, 2, 1])
# [ 7 16 25]
# print(three_dim[0, :, 0])
# [0 3 6]
# print(three_dim[0, 0, :])
#[0 1 2]
# print(three_dim[0])
# [[0 1 2]
#  [3 4 5]
#  [6 7 8]]

a_range = np.arange(2*2*2*3)
four_dim = a_range.reshape(2, 2, 2, 3)
# print(four_dim)
# [[[[ 0  1  2]
#    [ 3  4  5]]

#   [[ 6  7  8]
#    [ 9 10 11]]]


#  [[[12 13 14]
#    [15 16 17]]

#   [[18 19 20]
#    [21 22 23]]]]
# print(four_dim[:, 0, 0, 1])
# [ 1 13]


a_range = np.arange(6)
new_shape = (3, 2, 1)

a_range = np.reshape(a_range, new_shape)
# print(a_range)
# [[[0]
#   [1]]
#  [[2]
#   [3]]
#  [[4]
#   [5]]]