Remove duplicate from dictionary in python

Question

I have 5 lists in a dictionary I want to delete duplicates and retain the element that occurs in first list by comparing all lists available

dict = {1:[0,1,2,3], 2:[1,4,5], 3:[0,4,2,5,6], 4:[0,2,7,8], 5:[9]}

Output should look like this:

dict = {1:[0,1,2,3], 2:[4,5], 3:[6], 4:[7,8], 5:[9]}

Also not that there is no actual order to the keys/values in a dictionary. What happens if I look at 2 before I look at 1. Do you require the keys to be sorted numerically? — Frank Yellin
– Frank Yellin, Commented Nov 10, 2021 at 6:51
@sahasrara62 I Tried running a loop over the dictionary, stored them in two separate variables and compared them using a set operation — Shiju
– Shiju, Commented Nov 10, 2021 at 6:52
@j1-lee. You are correct. In 3.6, this was an implementation detail of CPython. But I see that in 3.7, it's been made official. Thanks for the correction. — Frank Yellin
– Frank Yellin, Commented Nov 10, 2021 at 16:53

j1-lee · Accepted Answer · 2021-11-10 06:59:50Z

2

You can make a set to store items that have been seen, and then sequentially update the dict according to the set:

d = {1:[0,1,2,3], 2:[1,4,5], 3:[0,4,2,5,6], 4:[0,2,7,8], 5:[9]}

seen = set()
for k, v in d.items():
    d[k] = [x for x in v if x not in seen]
    seen.update(d[k])

print(d) # {1: [0, 1, 2, 3], 2: [4, 5], 3: [6], 4: [7, 8], 5: [9]}

edited Nov 10, 2021 at 6:59

answered Nov 10, 2021 at 6:51

j1-lee

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U13-Forward · Accepted Answer · 2021-11-10 06:53:30Z

1

A one-liner with a dictionary comprehension:

>>> {k: [i for i in v if i not in sum(list(dct.values())[:idx], [])] for idx, (k, v) in enumerate(dct.items())}
{1: [0, 1, 2, 3], 2: [4, 5], 3: [6], 4: [7, 8], 5: [9]}
>>>

It filter and flattens all the values in the list before the certain key and filters the values not in there.

P.S. I renamed your dict to dct so it doesn't override the function name

answered Nov 10, 2021 at 6:53

U13-Forward

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1 Comment

Kelly Bundy Over a year ago

Nice, not even just quadratic but cubic runtime. Can you make it quartic? :-P

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