Question

       iluropoda_melanoleuca  bos_taurus  callithrix_jacchus  canis_familiaris
ailuropoda_melanoleuca     0        84.6                97.4                44
bos_taurus                 0           0                97.4              84.6
callithrix_jacchus         0           0                   0              97.4
canis_familiaris           0           0                   0                 0

这是我所拥有的python矩阵的简短版本。我在上三角形中有信息。是否有一个简单的功能可以将上三角形复制到矩阵的下三角形？

Answer 1

要在NumPy中执行此操作，不使用双循环，可以使用tril_indices。

>>> i_lower = np.tril_indices(n, -1)
>>> matrix[i_lower] = matrix.T[i_lower]  # make the matrix symmetric

请注意，您不要尝试混用tril_indices和triu_indices，因为它们都使用行主索引，即这不起作用：

>>> i_upper = np.triu_indices(n, 1)
>>> i_lower = np.tril_indices(n, -1)
>>> matrix[i_lower] = matrix[i_upper]  # make the matrix symmetric
>>> np.allclose(dist.T, dist)
False

Answer 2

如果我正确理解了这个问题，我相信这会有效

for i in range(num_rows):
    for j in range(i, num_cols):
        matrix[j][i] = matrix[i][j]

Answer 3

最简单，最快捷（无循环）的方法如下：

import numpy as np

X= np.array([[0., 2., 3.],
             [0., 0., 6.],
             [0., 0., 0.]])

X = X + X.T - np.diag(np.diag(X))
print(X)

#array([[0., 2., 3.],
#       [2., 0., 6.],
#       [3., 6., 0.]])

Answer 4

我猜这里有更好的一个：

>>> a = np.arange(16).reshape(4, 4)
>>> print(a)
array([[ 0,  1,  2,  3],
       [ 4,  5,  6,  7],
       [ 8,  9, 10, 11],
       [12, 13, 14, 15]])

>>> iu = np.triu_indices(4,1)
>>> il = (iu[1],iu[0])
>>> a[il]=a[iu]
>>> a
    array([[ 0,  1,  2,  3],
           [ 1,  5,  6,  7],
           [ 2,  6, 10, 11],
           [ 3,  7, 11, 15]])

Answer 5

如果U是上三角矩阵，则可以使用triu并转置以使其对称：

LDU = triu(U,1)+U.T

Answer 6

def inmatrix(m,n):#input Matrix Function 
    a=[]

    for i in range(m):

        b=[]

        for j in range(n):

            elm=int(input("Enter number in Pocket ["+str(i)+"]["+str(j)+"] "))

            b.append(elm)

        a.append(b)

    return  a

def Matrix(a):#print Matrix Function

    for i in range(len(a)):

        for j in range(len(a[0])):

            print(a[i][j],end=" ")

        print()
m=int(input("Enter number of row "))

n=int(input("Enter number of column"))

a=inmatrix(m,n) #call input Matrix function

Matrix(a)#print Matrix 

t=[]#create Blank list 

for i in range(m):

    for j in range(n):

        if i>j:#check upper triangular Elements 

            t.append(a[i][j])#add them in a list 

k=0#variable for list 

for i in range(m):

    for j in range(n):

        if i<j:

            a[i][j]=t[k]copy list item to lower triangular 

            k=k+1

Matrix(a)# print Matrix after change

将上三角形复制到python矩阵中的下三角形

6 个答案: