将外部矩阵旋转 n 步

Question

我有一个像

这样的矩阵

matrix1 = [1,2
           3,4]

matrix2 =[1,2,3
         4,5,6
         7,8,9]

我想像 r=1 这样按某个步长旋转这个矩阵，然后输出就像

output_matrix = [3,1
                 4,2]

output_matrix = [4,1,2
                 7,5,3
                 8,9,6]

我怎样才能做到这一点，步骤的旋转将是动态的。

我找到了这个解决方案，但这是用于固定旋转，即。步=1

def rotateMatrix(mat):

    if not len(mat):
        return

    top = 0
    bottom = len(mat)-1

    left = 0
    right = len(mat[0])-1

    while left < right and top < bottom:

        # Store the first element of next row,
        # this element will replace first element of
        # current row
        prev = mat[top+1][left]

        # Move elements of top row one step right
        for i in range(left, right+1):
            curr = mat[top][i]
            mat[top][i] = prev
            prev = curr

        top += 1

        # Move elements of rightmost column one step downwards
        for i in range(top, bottom+1):
            curr = mat[i][right]
            mat[i][right] = prev
            prev = curr

        right -= 1

        # Move elements of bottom row one step left
        for i in range(right, left-1, -1):
            curr = mat[bottom][i]
            mat[bottom][i] = prev
            prev = curr

        bottom -= 1

        # Move elements of leftmost column one step upwards
        for i in range(bottom, top-1, -1):
            curr = mat[i][left]
            mat[i][left] = prev
            prev = curr

        left += 1

    return mat


matrix =[[1,2,3],[4,5,6], [7,8,9]]

matrix = rotateMatrix(matrix)
# # Print modified matrix
print(matrix)

Answer 1

def rotate(r,matrix):
        '''for rotating the values on the outer ring of a matrix of size HxW'''
        height = len(matrix)
        width = len(matrix[0])
        matrixMap = mapMatrix(height,width)
        r %= len(matrixMap)
        rotatedMap = matrixMap[-r:]+matrixMap[:-r]
        newMatrix = {el:matrix[el[0]][el[1]] for el in matrixMap}
        for i,el in enumerate(rotatedMap):
            matrix[matrixMap[i][0]][matrixMap[i][1]] = newMatrix[el]
        return matrix

def mapMatrix(h,w):
        matrix = []
        for i in range(w):
            matrix.append((0,i))
        for i in range(1,h):
            matrix.append((i,w-1))
        for i in range(w-2,-1,-1):
            matrix.append((h-1,i))
        for i in range(h-2,0,-1):
            matrix.append((i,0))
        return matrix

这就是我将如何实现它，但我认为仍有一些改进的空间。支持负 r。希望这会有所帮助。

Answer 2

你可以结合旋转和转置来得到你想要的

import numpy as np

m = np.array([[1,2],[3,4]], int)
m1 = np.rot90(m)
m2 = m1.transpose()
print (m2)

这会给你

[[2 1]
 [4 3]]

随心所欲地改变。

其实你可以选择这样的元素

import numpy as np
m = np.array([[1,2],[3,4]], int)
# create tuple
new = (m[0][1],m[1][0])
# print list
print (list(new))

[2, 3]