661. Image Smoother 图像平滑化

Given a 2D integer matrix M representing the gray scale of an image, you need to design a smoother to make the gray scale of each cell becomes the average gray scale (rounding down) of all the 8 surrounding cells and itself. If a cell has less than 8 surrounding cells, then use as many as you can.

Example 1:

Input:
[[1,1,1],
 [1,0,1],
 [1,1,1]]
Output:
[[0, 0, 0],
 [0, 0, 0],
 [0, 0, 0]]
Explanation:
For the point (0,0), (0,2), (2,0), (2,2): floor(3/4) = floor(0.75) = 0
For the point (0,1), (1,0), (1,2), (2,1): floor(5/6) = floor(0.83333333) = 0
For the point (1,1): floor(8/9) = floor(0.88888889) = 0

Note:

1. The value in the given matrix is in the range of [0, 255].
2. The length and width of the given matrix are in the range of [1, 150].

给定一个表示图像灰度的二维整数矩阵M，您需要设计一个更平滑的方式，使每个单元格的灰度值成为所有8个周围单元格本身的平均灰度（舍入）。如果一个单元格具有小于8个周围的单元格，那么可以使用尽可能多的单元格。

class Solution(object):
    def imageSmoother(self, M):
        import math
        result = []
        for i in range(len(M)):
            row = []
            for j in range(len(M[i])):
                pos = [
                    [i - 1, j - 1], [i - 1, j], [i - 1, j + 1],
                    [i, j - 1], [i, j], [i, j + 1],
                    [i + 1, j - 1], [i + 1, j], [i + 1, j + 1]
                ]
                near = []
                for item in pos:
                    if item[0] >= 0 and item[0] < len(M) and item[1] >= 0 and item[1] < len(M[i]):
                        near.append(M[item[0]][item[1]])
                row.append(int(sum(near) / len(near)))
            result.append(row)
        return result

来自为知笔记(Wiz)