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This time I will bring you python How to use nonzero() in numpy, what are the precautions for using nonzero() in python numpy, the following is a practical case, one Get up and take a look.
nonzeroFunctionReturns the directory of nonzero elements.
The return value is a tuple, the two values are two dimensions respectively, and contain the directory values of non-zero elements in the corresponding dimensions.
import numpy as np A = np.mat([[0,1,2,3,4,3,2,1,0],[0,1,2,3,4,5,6,7,0]]) x = A.nonzero() #取出矩阵中的非零元素的坐标 print x #输出是一个元组,两个维度。一一对应, #返回非零元素在矩阵中的位置,前一个列表存放非零行坐标,后一个列表存放非零元素列坐标 #(array([0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1]), array([1, 2, 3, 4, 5, 6, 7, 1, 2, 3, 4, 5, 6, 7])) #放下来一一对应,即 #(array([0, 0, 0, 0, 0, 0, 0, 1, 1, 1, 1, 1, 1, 1]), #array([1, 2, 3, 4, 5, 6, 7, 1, 2, 3, 4, 5, 6, 7])) # (0,1) (0,2).............................. (1,6) (1,7) 坐标上的元素都是非0的 print A[x],'\n' #取出矩阵中的非零元素 #[[1 2 3 4 3 2 1 1 2 3 4 5 6 7]] B = np.mat([[1,1,0,1,0,1,0,0,1],[0,1,1,0,0,0,1,1,1]]) print np.nonzero(B) # 与B.nonzero()等价
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