How do you check if an element appears twice in a list python?

Without importing another function check if a list contains two of the same element

F.E list = [3,4,5,3] since 3 appears twice in the list return True

Thanks for the help

asked May 6, 2020 at 21:31

You can convert to set and check the resulting length:

len(set(data)) < len(data)

answered May 6, 2020 at 21:35

a_guesta_guest

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If you need to check if the element occurs exactly twice, you could do this:

l = [3,4,5,3]
if 2 in set([l.count(n) for n in l]):
    print('True')

answered May 6, 2020 at 21:39

ssharmassharma

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There are different approaches to solve this problem.

Solution 1: Use set()

if len(set())):
    return False
else:
    return True

Solution 2 : Use hash dictionary

def check_list(lst):
   hash_dict={}
   for elem in lst:
     if elem not in hash_dict:
        hash_dict[elem]=1
     else:
        return True
    return False

In the above solution, we add the elements in the hash dict and constantly check if it exists there, if it does then we return True. If the list has no duplicate or more than 2 elements then it will just return false.

Solution 3 : We can also use counter from collections

from collections import Counter
new_dict=Counter()
return True if 2 in new_dict.values() else False

answered May 6, 2020 at 22:00

I have a code that checks if something from a list is in string: if any(x in string for x in list) But how do I check if it appears twice or more than twice

any(string.count(x)>=2 for x in lst) Will be true if at least 1 item in lst appears twice or more in string.

Kirill Vidov Something like this: s = 'Sololearn' l = ['a', 'o', 'l', 'r', 'n'] print([x for x in l if s.count(x) >= 2]) # will only print 'o' and 'l'

Thank you everyone for the help

Kirill Vidov Show ur attempt

Kuba Siekierzyński can you please help if you can?

Kirill Vidov Ask if you have any doubt in it a=[1,2,3,"a",5,"b",4.8] print(*[i for i in a if type(i)==type("")]) Returns those elements from the list which are in string

Exactly, I would use count() to determine if there is more than one occurence of an element in a collection.

Abhay if any(x in string for x in list) >= 2, but that doesn't work

Questions : Check if an certain element appears twice in a list - Python

2022-10-02T13:15:46+00:00 2022-10-02T13:15:46+00:00

940

Without importing another function check if anycodings_python-3.x a list contains two of the same element

F.E list = [3,4,5,3] since 3 appears twice anycodings_python-3.x in the list return True

Thanks for the help

Total Answers 3

31

Answers 1 : of Check if an certain element appears twice in a list - Python

You can convert to set and check the anycodings_list resulting length:

len(set(data)) < len(data)

0

2022-10-02T13:15:46+00:00 2022-10-02T13:15:46+00:00Answer Link

mRahman

3

Answers 2 : of Check if an certain element appears twice in a list - Python

If you need to check if the element anycodings_list occurs exactly twice, you could do this:

l = [3,4,5,3]
if 2 in set([l.count(n) for n in l]):
    print('True')

0

2022-10-02T13:15:46+00:00 2022-10-02T13:15:46+00:00Answer Link

joy

3

Answers 3 : of Check if an certain element appears twice in a list - Python

There are different approaches to solve anycodings_list this problem.

Solution 1: Use set()

if len(set())):
    return False
else:
    return True

Solution 2 : Use hash dictionary

def check_list(lst):
   hash_dict={}
   for elem in lst:
     if elem not in hash_dict:
        hash_dict[elem]=1
     else:
        return True
    return False

In the above solution, we add the anycodings_list elements in the hash dict and constantly anycodings_list check if it exists there, if it does anycodings_list then we return True. If the list has no anycodings_list duplicate or more than 2 elements then anycodings_list it will just return false.

Solution 3 : We can also use counter anycodings_list from collections

from collections import Counter
new_dict=Counter()
return True if 2 in new_dict.values() else False

0

2022-10-02T13:15:46+00:00 2022-10-02T13:15:46+00:00Answer Link

joy

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