Remove duplicates nested list Python dependend on position

Question

in a nested list like the one below, I'd like to remove duplicates depending on the position.

[[1,2,3,4], [2,1,3,4], [1,2,3,4], [1,3,2,4]]

So every sub-list contains the same numbers, but in different order. If the order of the numbers is the same, I would like to delete this duplicate. So the list above should look like:

[[1,2,3,4], [2,1,3,4], [1,3,2,4]]

I have tried to write some code by myself, but since I am a beginner, there is no working result. I have tried:

result = []
for i in test_list:
    if i not in result:
        result.append(i)
return result

Or

tpls = [tuple(x) for x in test_list]
dct = list(dict.fromkeys(tpls))
dup_free = [list(x) for x in test_list]
return dup_free

Thanks!

EDIT2: Sorry everbody, the input was wrong so the code just could not work...

In your second solution, you wrote test_list instead of dct. — charon25
– charon25, Commented May 4, 2022 at 14:23

Sharim09 · Accepted Answer · 2022-05-04 14:22:54Z

1

lst = [[1,2,3,4], [2,1,3,4], [1,2,3,4], [1,3,2,4]]

new_lst = []
for a in lst:
    if a not in new_lst: # check if current element already in the new_lst or not.
        new_lst.append(a)
print(new_lst)

OUTPUT

[[1, 2, 3, 4], [2, 1, 3, 4], [1, 3, 2, 4]]

answered May 4, 2022 at 14:22

Sharim09

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11 Comments

Ic3Cub3 Over a year ago

I also have tried this code, however it does not seem to work

Sharim09 Over a year ago

@Ic3Cub3 But it's working.

Sharim09 Over a year ago

@Ic3Cub3 Can you copy this code and run on your computer?

Ic3Cub3 Over a year ago

I copied the code, ran it on my computer with the full list, but it only returns [[3, 4, 1, 2]]

Ic3Cub3 Over a year ago

yeah sorry my input list was just wrong. My bad...

|

inquirer · Accepted Answer · 2022-05-04 14:26:05Z

1

You can use pandas for this purpose.

import pandas as pd

aaa = {'date': ['2022-05-02', '2022-04-29', ' 2022-04-29', '2022-04-28 ', '2022-04-28 ', '2022-04-28 '],
       'id': ['A', 'A', 'B', 'A', 'B', 'C'], 'number': [397177, 53876, 191214, 75824, 483860, 51731]}

df = pd.DataFrame(aaa)
df = df.drop_duplicates().values

Output

[[1 2 3 4]
 [2 1 3 4]
 [1 3 2 4]]

answered May 4, 2022 at 14:26

inquirer

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Comments

Mohamed ASRI · Accepted Answer · 2022-05-04 14:28:02Z

1

First one is working run this code :

X = [[1,2,3,4], [2,1,3,4], [1,2,3,4], [1,3,2,4]]

def Rem_Dup(L) :
    result = []
    for i in L:
        if i not in result:
            result.append(i)
    return result

print(Rem_Dup(X))

answered May 4, 2022 at 14:28

Mohamed ASRI

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Comments

Timur Shtatland · Accepted Answer · 2022-05-04 14:28:41Z

1

For each sublist sublst in the original nested list, convert into tuple for lookup in the dictionary dct. Add to the resulting list without dups nodups only if we have not seen it:

lst = [[1,2,3,4], [2,1,3,4], [1,2,3,4], [1,3,2,4]]
nodups = []
dct = {}

for sublst in lst:
    tup = tuple(sublst)
    if tup not in dct:
        dct[tup] = 1
        nodups.append(sublst)
    else:
        pass
print(nodups)
# [[1, 2, 3, 4], [2, 1, 3, 4], [1, 3, 2, 4]]

answered May 4, 2022 at 14:28

Timur Shtatland

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Comments

Nin17 · Accepted Answer · 2022-05-04 14:35:22Z

1

You can do it in one line with a list comprehension:

a = [[1,2,3,4], [2,1,3,4], [1,2,3,4], [1,3,2,4]]
[j for i, j in enumerate(a) if j not in a[i+1:]]

Output:

[[2, 1, 3, 4], [1, 2, 3, 4], [1, 3, 2, 4]]

Note: This will choose the last occurrence of that sublist in the original list if you care about the ordering

Edit: If you care about ordering, you can go through the list backwards and then reverse the result:

[j for i, j in enumerate(reversed(a)) if j not in list(reversed(a))[i+1:]][::-1]

Output:

[[1, 2, 3, 4], [2, 1, 3, 4], [1, 3, 2, 4]]

edited May 4, 2022 at 14:35

answered May 4, 2022 at 14:29

Nin17

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