Trying to use delete duplicates while using any() to go through the

Question

I am a beginner learning Python and was trying to remove duplicates from list while using any (Trying to learn any() and all()).

def remove_duplicates(x):
    l=0
    for i,item in enumerate(x):
        if any(l==item for l in x)==True:
            print (i,item)
            x=del x[i]
    return(x)
x=[1,2,3,1]
print (remove_duplicates(x))

I am getting the following result.

0 1
1 3
[2, 1]

Instead of [2,3,1].

It is generally a bad idea to modify an array as you iterate over it. Work on a copy instead. — Owen, Aug 02 '16 at 01:26
Since `item` is take from `x`, `any(l == item for l in x)` is *always* going to be true. — chepner, Aug 02 '16 at 01:29
@Owen Thank you very much. Forgot that elements would slide down. Found an explination with examples here. https://unspecified.wordpress.com/2009/02/12/thou-shalt-not-modify-a-list-during-iteration/ — Umesh Sai Gurram, Aug 02 '16 at 01:31
@UmeshSaiGurram `if any(l==item for l in x)==True:` is redundant. Just use `if any(l==item for l in x):` — juanpa.arrivillaga, Aug 02 '16 at 01:33
@junapa Thank you guys.I understood my mistakes. Was trying to learn any all, learnt more. — Umesh Sai Gurram, Aug 02 '16 at 05:16

Dorival Neto · Accepted Answer · 2016-08-02T01:50:02.913

1

I understand that you are trying to learn the use of 'any' and 'all', but it is not a good idea to remove or delete a term while iterating over a list. This is the cause of the unexpected behaviour of your code. However, you can use a set to get the existing items in a list/tuple without duplicates. For instance:

a = [0,1,3,1,0,3,4,6,4,5]
b = set(a)
print(b)

It returns: set([0,1,3,4,5,6)]

Please notice that the type of b is 'set'. If you want b to be list you can use:

b = list(set(a))

edited Aug 02 '16 at 01:50

answered Aug 02 '16 at 01:39

Dorival Neto

36
5

1

You might want to clarify that order is not preserved. – OneCricketeer Aug 02 '16 at 01:44
@cricket_007 You are right, it is important to mention the order issue. Thank you for editing my answer, I did not know how to do it. – Dorival Neto Aug 02 '16 at 01:54
Welcome. You can see how to better format question and answers [here](http://stackoverflow.com/editing-help) – OneCricketeer Aug 02 '16 at 01:56

score 0 · Answer 2 · answered Aug 02 '16 at 01:48

0

If you don't care the order of the sequence, simply do:

list(set(x))

answered Aug 02 '16 at 01:48

xblymmx

39
2
3

1

His intention is to learn all and any, so this answers helps with nothing at all – rafaelc Aug 02 '16 at 01:51

Trying to use delete duplicates while using any() to go through the

2 Answers2