[英]Numpy extract values on the diagonal from a matrix
My question is similar(the expanded version) to this post: Numpy extract row, column and value from a matrix . 我的问题与此帖子类似(扩展版本): Numpy从matrix提取行,列和值 。 In that post, I extract elements which are bigger than zero from the input matrix, now I want to extract elements on the diagonal , too. 在那篇文章中,我从输入矩阵中提取大于零的元素,现在我也想在对角线上提取元素 。 So in this case, 所以在这种情况下
from numpy import *
import numpy as np
m=np.array([[0,2,4],[4,0,0],[5,4,0]])
dist=[]
index_row=[]
index_col=[]
indices=np.where(matrix>0)
index_col, index_row = indices
dist=matrix[indices]
return index_row, index_col, dist
we could get, 我们可以得到,
index_row = [1 2 0 0 1]
index_col = [0 0 1 2 2]
dist = [2 4 4 5 4]
and now this is what I want, 现在这就是我想要的
index_row = [0 1 2 0 1 0 1 2]
index_col = [0 0 0 1 1 2 2 2]
dist = [0 2 4 4 0 5 4 0]
I tried to edit line 8 in the original code to this, 我试图在原始代码中编辑第8行,
indices=np.where(matrix>0 & matrix.diagonal)
but got this error, 但是出现了这个错误,
How to get the result I want? 如何获得我想要的结果? Please give me some suggestions, thanks! 请给我一些建议,谢谢!
You can use following method: 您可以使用以下方法:
Here is the code: 这是代码:
m=np.array([[0,2,4],[4,0,0],[5,4,0]])
mask = m > 0
np.fill_diagonal(mask, True)
m[mask]
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