填充空嵌套列表- for循环与列表理解

nested_list = [[1, 2, None], [3, None, 4], [None, 5, 6]]

# 定义要填充的值
fill_value = 0

# 使用for循环遍历嵌套列表，并将空元素填充为指定的值
for i in range(len(nested_list)):
    for j in range(len(nested_list[i])):
        if nested_list[i][j] is None:
            nested_list[i][j] = fill_value

print(nested_list)

[[1, 2, 0], [3, 0, 4], [0, 5, 6]]

nested_list = [[1, 2, None], [3, None, 4], [None, 5, 6]]

# 定义要填充的值
fill_value = 0

# 使用列表理解遍历嵌套列表，并将空元素填充为指定的值
nested_list = [[fill_value if element is None else element for element in sublist] for sublist in nested_list]

print(nested_list)

[[1, 2, 0], [3, 0, 4], [0, 5, 6]]