Question

以下代码适用于非常具体的情况，如下所述。我想概括一下。我正在尝试打印出阵列的子数组。

import numpy as np

alpha = input("input this number... ")
X = np.arange(alpha**2).reshape(alpha,alpha) #square matrix

beta  = input("a number in the matrix X")

if(beta > alpha**2): 
    print("must pick number inside array"), exit() 

print(X) #correct square matrix

00 01 02 03 04
05 06 07 08 09
10 11 12 13 14 
15 16 17 18 19
20 21 22 23 24

我想打印这个矩阵X的3x3子数组，与我选择的alpha无关（独立于3x3方形或5x5方形矩阵等）。如下图所示。

Answer 1

您可以尝试：

import numpy as np

alpha = input("input this number... ")
X = np.arange(alpha**2).reshape(alpha,alpha) #square matrix

beta  = input("a number in the matrix X")
if(beta > alpha**2): 
    print("must pick number inside array"), exit() 
row, col = beta // alpha, beta % alpha # This will give you the idxs of beta number in array
subsize = input("a size of submatrix you want to get")
border = (subsize - 1) // 2

subrand = np.array(X)[row - border: row + border + 1, col - border: col + border + 1]
print(subrand)

Answer 2

如果数组中的所有值都是唯一的（正如您在问题中的两个示例中所示）：

[[i,j]] = numpy.argwhere(X==beta)
print(X[i-1:i+2,j-1:j+2])

此代码在2D数组中查找(i, j)索引，使X[i,j]等于beta值。因此X[i-1:i+2,j-1:j+2]是3x3数组，中心值为beta，除非beta位于矩阵的边缘。

即使在边缘也能获得所有可用值：

print(X[max(i-1,0):i+2,max(j-1,0):j+2])

打印子阵列数组

2 个答案: