python实现由数组生成对称矩阵

[[0,1,2,3,4],
 [1,0,5,6,7],
 [2,5,0,8,9],
 [3,6,8,0,10],
 [4,7,9,10,0]]

def semi_to_full(m):
    import numpy as np
    n = len(m)
    n_matrix = int((1+int((1+8*n)**0.5))/2)
    semi_matrix = np.zeros((n_matrix,n_matrix),dtype='int32')

    start_index = 0
    for row in range(n_matrix-1):
        end_index = start_index+(n_matrix-1-row)
        semi_matrix[row,row+1:]=m[start_index:end_index]
        start_index = end_index

    full_matrix = semi_matrix+semi_matrix.T
    
    return full_matrix