CODEWITHSUNDEEP
pythonlistnested-lists
Prayag Bhatia
Prayag Bhatia

Reputation: 406

Remove duplicates from a nested list

I have a list 

A = [['1'],['1','2'],['1','2','3','1','2'],['3','3','3']]

and I want to make my list to

A = [['1'],['1','2'],['1','2','3'],['3']]

ie I want to remove duplicate elements within the elements in a list ..

Upvotes: 1

Views: 974

Answers (3)

Djaouad
Djaouad

Reputation: 22766

One-liner (If order doesn't matter) :

A = [['1'],['1','2'],['1','2','3','1','2'],['3','3','3']]
A = [list(set(a)) for a in A]
print(A) # => [['1'], ['2', '1'], ['3', '2', '1'], ['3']]

One-liner (If order matters) :

A = [['1'],['1','2'],['1','2','3','1','2'],['3','3','3']]
A = [sorted(set(a), key=a.index) for a in A]
print(A) # => [['1'], ['1', '2'], ['1', '2', '3'], ['3']]

Upvotes: 3

jferard
jferard

Reputation: 8180

A functional version, with functools:

>>> import functools
>>> A = [['1'],['1','2'],['1','2','3','1','2'],['3','3','3']]
>>> print ([functools.reduce(lambda result,x:result if x in result else result+[x], xs, []) for xs in A])
[['1'], ['1', '2'], ['1', '2', '3'], ['3']]

The lambda function adds an element to the result list only if that element is not present in the list. Not very efficient, but keeps the order of elements.

Also note that with Python 2, you don't need to import functools: reduce is a builtin function.

Upvotes: 1

Ajax1234
Ajax1234

Reputation: 71451

You can use a generator:

def remove_dups(l):
   for a in l:
      new_l = []
      for b in a:
          if b not in new_l:
             new_l.append(b)
      yield new_l

A = [['1'],['1','2'],['1','2','3','1','2'],['3','3','3']]
print(list(remove_dups(A)))

Output:

[['1'], ['1', '2'], ['1', '2', '3'], ['3']]

Upvotes: 0

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