Python代码打印一个不需要的行

Question

我不知道是什么导致我的代码在执行结束时打印“无”。这段代码应该读取一个包含0和1矩阵的txt文件，并打印由1构成的正交“孤岛”的坐标

from itertools import groupby
from operator import itemgetter

def matrixReader(inputFile): # Reads the file and creates the matrix map.
    w, h = map(int, inputFile.readline().strip().split())
    matrix = [list(map(int, line.strip())) for line in inputFile]
    return matrix, h, w

def matrixAdvancedSweeper(matrix, h, w): # Swipes the matrix map after NEW land chunks and makes a tuple for each piece of land.
    islandCount = 1
    landCoordinates = []
    for y in range(h):
        for x in range(w):
            if matrix[y][x] == 1:
                islandCount += 1
                islandSorter(matrix, y, x, islandCount)
            if matrix[y][x] > 1:
                landCoordinates.append((matrix[y][x]-1, y, x)) # Creates a list of tuples with the number of the island, height position and width position.
    return sorted(landCoordinates, key=itemgetter(0, 1)) # Sorts the list of tuples (first) by number of the island and (second) by height position.

def islandSorter(m, h, w, c): # Recursive function to enumerate and hide any land attached to a chunk already swiped.
    if m[h][w] == 1:
        m[h][w] = c
        if w < len(m[0]) - 1: islandSorter(m, h, w + 1, c)
        if h < len(m) - 1: islandSorter(m, h + 1, w, c)
        if w > 0: islandSorter(m, h, w - 1, c)
        if h > 0: islandSorter(m, h - 1, w, c)

def coordinatePrinter(sortedCoordinates): # Prints the groups of coordinates that forms each island.
    for key, group in groupby(sortedCoordinates, lambda x: x[0]): # Creates groups using the first item of the tuples as key and traverses those returning each key and group.
        print('____________\n  Island %s\nCoordinates:' % (key))
        for tile in group:
            print(' x %s   y %s' % (tile[1], tile[2]))

with open('TestFile.txt') as inputFile: # Opens the defined file to execute the nested code and than closes it.
    print(coordinatePrinter(matrixAdvancedSweeper(*matrixReader(inputFile))))

以下是为进行测试而应读取的文件（TestFile.txt）的示例：

4 4
1110
0000
0000
0110

Answer 1

问题是调用方法时使用的print语句：

with open('TestFile.txt') as inputFile: # Opens the defined file to execute the nested code and than closes it.
    print(coordinatePrinter(matrixAdvancedSweeper(*matrixReader(inputFile))))

print语句的返回类型是None。因此，函数执行完成后，print语句将退出None

简单的解决方法是删除print，如：

with open('TestFile.txt') as inputFile: # Opens the defined file to execute the nested code and than closes it.
    coordinatePrinter(matrixAdvancedSweeper(*matrixReader(inputFile)))

因为您已经在coordinatePrinter函数中打印值了