计算一个NumPy数组的对角线元素的总和

有时我们需要找到右上角、左上角、右下角或左下角的对角线元素之和。Numpy为我们提供了使用numpy.trace()和numpy.diagonal()方法计算不同对角线元素之和的工具。

方法1：使用numpy.trace()寻找对角线元素的和。

语法： numpy.trace(a, offset=0, axis1=0, axis2=1, dtype=None, out=None)

例子1：对于3X3的Numpy矩阵来说

# importing Numpy package
import numpy as np
  
# creating a 3X3 Numpy matrix
n_array = np.array([[55, 25, 15],
                    [30, 44, 2],
                    [11, 45, 77]])
  
# Displaying the Matrix
print("Numpy Matrix is:")
print(n_array)
  
# calculating the Trace of a matrix
trace = np.trace(n_array)
  
  
print("\nTrace of given 3X3 matrix:")
print(trace)

输出:

例子2：对于4X4的Numpy矩阵来说

# importing Numpy package
import numpy as np
  
# creating a 4X4 Numpy matrix
n_array = np.array([[55, 25, 15, 41],
                    [30, 44, 2, 54],
                    [11, 45, 77, 11],
                    [11, 212, 4, 20]])
  
# Displaying the Matrix
print("Numpy Matrix is:")
print(n_array)
  
# calculating the Trace of a matrix
trace = np.trace(n_array)
  
  
print("\nTrace of given 4X4 matrix:")
print(trace)

输出:

方法2：使用numpy.diagonal()寻找对角线元素之和。

语法 :

numpy.diagonal(a, offset=0, axis1=0, axis2=1

例子1：对于3X3的Numpy矩阵来说。

# importing Numpy package
import numpy as np
  
# creating a 3X3 Numpy matrix
n_array = np.array([[55, 25, 15],
                    [30, 44, 2],
                    [11, 45, 77]])
  
# Displaying the Matrix
print("Numpy Matrix is:")
print(n_array)
  
# Finding the diagonal elements of a matrix
diag = np.diagonal(n_array)
  
print("\nDiagonal elements are:")
print(diag)
  
print("\nSum of Diagonal elements is:")
print(sum(diag))

输出:

例子2：对于5X5的Numpy矩阵来说

# importing Numpy package
import numpy as np
  
# creating a 5X5 Numpy matrix
n_array = np.array([[5, 2, 1, 4, 6],
                    [9, 4, 2, 5, 2],
                    [11, 5, 7, 3, 9],
                    [5, 6, 6, 7, 2],
                    [7, 5, 9, 3, 3]])
  
# Displaying the Matrix
print("Numpy Matrix is:")
print(n_array)
  
# Finding the diagonal elements of a matrix
diag = np.diagonal(n_array)
  
print("\nDiagonal elements are:")
print(diag)
  
print("\nSum of Diagonal elements is:")
print(sum(diag))

输出: