如何在网格中查找邻居

Question

我必须创建一个函数来计算网格中给定单元格周围的所有邻居。不仅如此，它还必须返回所有等于 1 的“活邻居”，而不返回中间单元格的值。我一直在阅读论坛，试图准确理解我将如何做到这一点，但我仍然很困惑。

这是迄今为止我的代码以及老师给我的说明：

def countLiveNeighbors( grid, rowIndex, columnIndex ):
    # TODO - Find the number of grid rows (HINT: use the len() of the grid)

    rows = len(grid)
    
    # TODO - Find the number of grid columns (HINT: use the len() of the first row)

    cols = len(grid[0])

    # TODO - Compute neighbor indices.
    #        Make sure all indices are positive!
    #        Make sure all indices are not too large!
    r = rowIndex
    c = columnIndex
    for row in rows:
        for col in cols:
            if col >= 0:
               grid[r][c] + 1
            else:
                grid[r][c] - 1
    # TODO - Count the number of live neighbors.
    #        Do NOT count the cell in the middle, only neighbors!


    # TODO - Return the number of live neighbors




# make a test grid to test you function on
testGrid = [[0,0,0,0,0],
            [0,1,1,0,0],
            [0,1,1,0,0],
            [0,0,0,0,0]]


# count the live neighbors for a cell at some row and column
row = 1
col = 2

neighborCount = life_module.countLiveNeighbors( testGrid, row, col )

print( "cell at row", row, "and col", col, "has", neighborCount, "live neighbors" )

我不明白我会采取什么步骤来找到邻居并只计算存活的邻居。如果有人可以解释它是如何完成的并纠正我的代码，我将非常感激。

Answer 1

给定一些单元格

grid[r][c]

，对应于上、下、左、右邻居的位置是

grid[r - 1][c]

、

grid[r + 1][c]

、

grid[r][c - 1]

和

grid[r][c + 1]

。如果需要对角邻居，那么应该很容易根据 4 个方向找出它们的索引。显然，您必须检查索引是否在数组的范围内，这可以通过

r in range(rows) and c in range(cols)

来完成。

执行此操作的代码如下所示：

def countLiveNeighbors( grid, rowIndex, columnIndex):
    rows = len(grid)
    cols = len(grid[0])
    r, c = rowIndex, columnIndex
    live_count = 0
    #Coordinates corresponding to up, down, left, right
    dirs = [(-1, 0), (1, 0), (0, -1), (0, 1)] 
    for x, y in dirs: 
        new_r, new_c = r + x, c + y
        if new_r in range(rows) and new_c in range(cols) and grid[new_r][new_c] == 1:
            live_count += 1
            
    return live_count

# make a test grid to test you function on
testGrid = [[0,0,0,0,0],
            [0,1,1,0,0],
            [0,1,1,0,0],
            [0,0,0,0,0]]


# count the live neighbors for a cell at some row and column
row = 1
col = 2

neighborCount = life_module.countLiveNeighbors( testGrid, row, col )

print( "cell at row", row, "and col", col, "has", neighborCount, "live neighbors" )