Turn a list into a list which each item has multiplicity 1

Question

Suppose we have a list, where every item has its frequency: 1, 2, 3 , etc. Then, from this list, I would like to get another list where every item has a frequency 1.

For example, the original list is:

A = [1, 2, 3, 1, 2, 5, 6, 7, 8, 5]

The idea is to get another list such as:

B = [1, 2, 3, 5, 6, 7, 8]

How can I do it?

This is what I implemented in Python:

for i in range(10):
    k = i
    item1 = A[k]
    for j in range(k):
        l = j
        item2 = A[l]
        if (item1 != item2):
            B.append(item1)
            break

But I get:

B = [1, 2, 5]

Can someone please help me? Thanks in advance.

So erase all duplicates starting to erase from the right? – FailingCoder Mar 09 '19 at 21:56 — FailingCoder, Mar 09 '19 at 21:56
just use `list(set(A))` – chickity china chinese chicken Mar 09 '19 at 22:09 — chickity china chinese chicken, Mar 09 '19 at 22:09
This question is a repeat, as posted above. – bart cubrich Mar 09 '19 at 22:11 — bart cubrich, Mar 09 '19 at 22:11

score 0 · Answer 1 · edited Mar 09 '19 at 22:09

0

I am not sure if there is a built-in function for this but I would rather do this:

def Remove(duplicate): 
    final_list = [] # make an empty list
    for num in duplicate: # iterate over the given list
        if num not in final_list: # if number is not in the list, push it to the list.
            final_list.append(num) 
    return final_list

edited Mar 09 '19 at 22:09

MSeifert

145,886
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answered Mar 09 '19 at 22:01

Taimoor Ali

158
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7

score 0 · Answer 2 · answered Mar 09 '19 at 22:05

You can use unique_everseen in order to remove duplicates and preserve order:

from  more_itertools import unique_everseen

A = [1, 2, 3, 1, 2, 5, 6, 7, 8, 5]
B = list(unique_everseen(items))
print(B)
>>> [1, 2, 3, 5, 6, 7, 8]

If you don't have more_itertools installed on your machine, you can install it using PyPi:

pip install more-itertools

score 0 · Answer 3 · edited Mar 09 '19 at 22:56

0

A good method for this is to use the 'set' data structure.

a = [1, 2, 3, 1, 2, 5, 6, 7, 8, 5]
a_prime=list(set(a))
print (a_prime)
Out:
[1, 2, 3, 5, 6, 7, 8]

edited Mar 09 '19 at 22:56

Taimoor Ali

158
1
7

answered Mar 09 '19 at 22:10

bart cubrich

1,184
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14
41

Turn a list into a list which each item has multiplicity 1

3 Answers3