如何确定给定数字是否在数字列表中？

Question

我想制作一个函数，以发现给定的数字是否在数字列表中。如何修复以下代码，以便它适用于由列表组成的列表？

lst = [[1, 2], [3, 4],[5, 6, 7]]
num = 9

def in_list_of_list(lst: list) -> bool:

    i = 0

    while i < len(lst) and lst[i] != num:
        i = i + 1
    return i < len(lst)
    
print(in_list_of_list(lst))

Answer 1

您可以首先将列表弄平，然后轻松地在平面上检查：

lst = [[1, 2], [3, 4], [5, 6, 7]]

num = 9


def in_list_of_list(lst: list) -> bool:
    flat_list = [item for sublist in lst for item in sublist]
    return num in flat_list


print(in_list_of_list(lst))

Answer 2

您询问该项目是否在列表的任何元素内部

def in_list_of_list(lst: list, item:object) -> bool:
    for sublist in lst:
        if item in sublist:
            return True
    return False

和快速测试

>>> lst = [[1, 2], [3, 4],[5, 6, 7]]
>>> in_list_of_list(lst, 9)
False
>>> in_list_of_list(lst, 7)
True
>>> 

Answer 3

lst = [[1, 2], [3, 4],[5, 6, 7]]
num = 9

def in_list_of_list(lst: list) -> bool:
    new_lst = []
    for a in lst:
        new_lst.extend(a) # add element from the inner list to new_list.
    return num in new_lst  # return True if the num inside the list else False.

print(in_list_of_list(lst))