Realization of Array Remodeling in numpy Series

Directory 1. Array remodeling 1.1 1-dimensional array remodeling
1.2 Multidimensional array remodeling
2. Array transpose

1. Array remodeling

Array remodeling is to change the shape of an array. For example, the original array with 3 rows and 4 columns is reshaped into an array with 4 rows and 3 columns. Realization of array remodeling by reshape method in numpy

1.1 1-dimensional array remodeling

1-dimensional array remodeling is to reshape an array from a 1-row or 1-column array to a multi-row and multi-column array.

Create a 1-dimensional array first

import numpy as np
​arr = np.arange(8)
print(arr)

result:
[0 1 2 3 4 5 6 7]

The above array can be converted to either a 2-row 4-column multidimensional array or a 4-row 2-column multidimensional array

1.1. 1 Reshape an array into a multidimensional array with 2 rows and 4 columns

print(arr.reshape(2, 4))

result:
[[0 1 2 3]
[4 5 6 7]]

1.1. 2 Rebuilding an array to a multidimensional array with 4 rows and 2 columns

print(arr.reshape(4, 2))

result:
[[0 1]
[2 3]
[4 5]
[6 7]]

Note: No matter 2 rows and 4 columns or 4 rows and 2 columns, as long as the number of values in the array after remodeling is equal to the number of values in the 1-dimensional array before remodeling.

1.2 Multidimensional array remodeling

Create a multidimensional array first

import numpy as np
arr = np.array([[1, 2, 3], [4, 5, 6], [7, 8, 9], [10, 11, 12]])
print(arr)

result:
[[ 1 2 3]
[ 4 5 6]
[ 7 8 9]
[10 11 12]]

Similarly, the above array can be converted to either a 3-row, 4-column multidimensional array or a 2-row, 6-column multidimensional array

1.2. 1 Rebuilding an array to a multidimensional array with 3 rows and 4 columns

print(arr.reshape(3, 4))

result:
[[ 1 2 3 4]
[ 5 6 7 8]
[ 9 10 11 12]]

1.2. 2 Reshape the array into a multidimensional array with 2 rows and 6 columns

print(arr.reshape(2, 6))

result:
[[ 1 2 3 4 5 6]
[ 7 8 9 10 11 12]]

Note: We can also reshape a 4-row 3-column multidimensional array into a 3-row 4-column or 2-row 6-column multidimensional array, as long as the number of values in the reshaped array is equal to the number of values in the previous 1-dimensional array.

2. Array transpose

Array transposition is to rotate the rows of an array into columns, using the method of. T. Transposition can be regarded as a special kind of remodeling here.

import numpy as np
arr = np.array([[1, 2, 3], [4, 5, 6], [7, 8, 9], [10, 11, 12]])
print(arr)

result:
[[ 1 2 3]
[ 4 5 6]
[ 7 8 9]
[10 11 12]]

print(arr.T)

result:
[[ 1 4 7 10]
[ 2 5 8 11]
[ 3 6 9 12]]