Question

我想检查某个值是否在嵌套列表中。我有一个主列表，其中包含更多可以包含更多列表的列表等等。就像这样：

[['Hey', 1], 0, 0, 0, ['Heyyy', 1], [[['Hi', 1], ['Hiii', 1]], 
['Hola',    1]], ['Hollaa', 2], ['Hallo', 1], 0, ['Hallooo', 1]]

现在我想检查一下是否有＆＃39; Hiii＆＃39;在其中一个列表中，如果这是True，我想更改列表的第二个值。

到目前为止，我尝试使用递归和生成器，但我实际上并不知道这是如何工作的。我不知道如何更改列表的第二个值。 ..

def search(nested_list):
    for value in nested_list:
        for subvalue in search(value):
            yield subvalue

感谢您的帮助！

Answer 1

假设：

LoL=[['Hey', 1], 0, 0, 0, ['Heyyy', 1], [[['Hi', 1], ['Hiii', 1]], 
['Hola',    1]], ['Hollaa', 2], ['Hallo', 1], 0, ['Hallooo', 1]]

要检查，如果某个值位于列表列表中，请首先使用生成器来展平任意列表列表：

def flatten(it):
    for x in it:
        if (isinstance(x, collections.Iterable) and
            not isinstance(x, str)):
            yield from flatten(x)
        else:
            yield x

然后使用any：

>>> any(x=="Hiii" for x in flatten(LoL))
True
>>> any(x=="BooHoo" for x in flatten(LoL))
False

更改列表清单：

def LoLedit(li, tgt, nv):
    if isinstance(li, list):
        if li[0]==tgt: 
            li[1]=nv
        else:
            for next_item in li:
                LoLedit(next_item, tgt, nv)
    return li   

>>> LoLedit(LoL,"Hiii", "Changed")
[['Hey', 1], 0, 0, 0, ['Heyyy', 1], [[['Hi', 1], ['Hiii', 'Changed']], ['Hola', 1]], ['Hollaa', 2], ['Hallo', 1], 0, ['Hallooo', 1]]

Answer 2

你走在正确的轨道上，但你不需要这里的生成器功能 - 简单的递归w / find＆amp;改变就足够了：

def search(source, find, new_value):
    if isinstance(source, list):  # no point searching in non-lists
        if find in source:
            source[1] = new_value
        else:
            for item in source:
                search(item, find, new_value)


data = [['Hey', 1], 0, 0, 0, ['Heyyy', 1], [[['Hi', 1], ['Hiii', 1]], ['Hola', 1]],
        ['Hollaa', 2], ['Hallo', 1], 0, ['Hallooo', 1]]

search(data, "Hiii", 5)

print(data)
# prints:
# [['Hey', 1], 0, 0, 0, ['Heyyy', 1], [[['Hi', 1], ['Hiii', 5]], ['Hola', 1]],
# ['Hollaa', 2], ['Hallo', 1], 0, ['Hallooo', 1]]

这假设您在找到商品后不想进行更深入的搜索。

Answer 3

一个非常基本的递归函数，用于查找和更新值。

{
"fld_status": "Online",
"fld_server_update": "Friday, May, 19, 2017 10:33:53 AM Central Daylight Time",
"fld_signalstr": "42%",
"fld_power": "23.98 Volts",
"fld_battery": "7.538 Volts",
"fld_temp": "72 Degrees F",
}

Answer 4

另一种检查某个值是否在嵌套列表（列表列表）中的方法可以使用recursion来完成：

# Flatten the list of lists into a simple list
def flatten_list(my_list, final=None):                                       
    if final is None:                                               
        final = []

    for i in my_list:
        if isinstance(i, list):
            flatten_list(i, my_list)
        else:
            final.append(i)

    return final

a = [['Hey', 1], 0, 0, 0, ['Heyyy', 1], [[['Hi', 1], ['Hiii', 1]], 
['Hola',    1]], ['Hollaa', 2], ['Hallo', 1], 0, ['Hallooo', 1]]

check_element = lambda x, y: x in flatten_list(y)

# Some tests:
print(check_element('hey', a))
print(check_element('Hey', a))
print(check_element('Heyyy', a))
print(check_element('Hiii', a))
print(check_element(1, a))
print(check_element('foo', a))

输出：

False
True
True
True
True
False

如何检查值是否在嵌套列表中

4 个答案: