Python-在列表列表中查找列表

Question

I have a list of lists, where each list may be of arbitrary length for example:

list_of_lists = [[2, 2, 2, 3], [2, 3, 4], [2, 2, 6]]

I need a way to search that list of lists for a specific list. For example, a contains() function which would return True below:

list_of_lists.contains([2, 2, 6])

I have seen answers where the "inner lists" can be converted into tuples, but that doesn't help me here. Is there a library out there that has this function?

Answer 1

Using in :

list_of_lists = [[2,2,2,3],[2,3,4],[2,2,6]]

if [2,2,6] in list_of_lists:
    print("found")
else:
    print("not found")

OUTPUT :

found

Similarly, let's say the last list in the nested list was: [2, 2, 6, 8]

list_of_lists = [[2,2,2,3],[2,3,4],[2,2,6,8]]

if [2,2,6] in list_of_lists:
    print("found")
else:
    print("not found")

OUTPUT :

not found

EDIT :

While I was at it, if you wanted to have a boolean value for the existance of the list:

def chkList(lst):
    return True if lst in list_of_lists else False

list_of_lists = [[2,2,2,3],[2,3,4],[2,2,6]]
print(chkList([2,2,6]))

OUTPUT :

True

Answer 2

Use in :

print([2,2,6] in list_of_lists)

Or use __contains__ :

 
 
 
 
  
  
  print(list_of_lists.__contains__([2,2,6]))
 
 
  

(DON'T USE __contains__ , HIGHLY UN-RECOMENDED)

Answer 3

There are multiple answers suggesting to use in or == to see if the list contains the element (another list).
However, if you do not care about the order of the elements in the lists you are comparing, here is a solution to that.

import collections

# 'list_' is the list we are searching for in a bigger list 'list_of_lists'
for element in list_of_lists:
    if collections.Counter(element) == collections.Counter(list_) :
        return True

The above solution requires the elements to be hashable.

If you find collections too complicated to understand, you can simply use set(list_) == set(element) .

The above methods require elements to be hashable. If the elements are not hashable but sortable, you can use sorted(list_)==sorted(element) .

Answer 4

What if you dosomething like

if any(list == [2, 2, 6] for list in list_of_lists):
    #execute whatever code you want for this case

Answer 5

Just in case you needed a more generic solution checking if your target list is actually an ordered sublist of one of inner lists. The trick would be converting the list into a string representation that allows efficient substring checking.

>>> list_of_lists = [[2,2,2,3],[2,3,4],[2,2,6,8]]
>>> serialize = lambda x: ','.join(map(str,x))
>>> any(serialize([2,2,6]) in serialize(item) for item in list_of_lists)
True
>>> any(serialize([2,2,7]) in serialize(item) for item in list_of_lists)
False

Answer 6

Please check the following code from ipython

In [18]: list
Out[18]: [[1, 2, 3], [4, 5, 6], [3, 2, 4]]

In [19]: def contains(sublist):
             if sublist in list:
                  return True
             else:
                  return False
   ....:             

In [20]: contains([1,2,3])
True

In [21]: contains(2)
False

In [22]: