Can't delete not last single object

Question

My code should recieve a list of numbers and then output on the screen the only numbers which repeat more then once. I don't know why but it don't work with the numbers in the middle of list. My code:

a = [int(i) for i in (input().split())]
a.sort()
for number in a:
    if a.count(number)==1:
        a.remove(number)
    else:
        a.remove(a.count(number)-a.count(number)+number)
for number in a:
    print(number, end=' ')

I tried changing if on while on 4th string, but then the last number is left in the list. It should work like:

Sample Input 1: 4 8 0 3 4 2 0 3 Sample Output 1: 0 3 4

Sample Input 2: 10 Sample Output 2:

Sample Input 3: 1 1 2 2 3 3 Sample Output 3: 1 2 3

Sample Input 4: 1 1 1 1 1 2 2 2 Sample Output 4: 1 2

`a.count(number)-a.count(number)+number` = `number`, right? You should use `collections.Counter` for this task. — qvpham, Jul 05 '16 at 08:28

score 1 · Accepted Answer · edited May 23 '17 at 12:08

You could approach this problem using set instead:

a = list(map(int, input().split()))
print(" ".join(map(str, set(i for i in a if a.count(i) > 1))))

Explanation:

Firstly, it looks like you should read up on the map function. Instead of a = [int(i) for i in (input().split())], you can just use list(map(int, input().split())), which is much more Pythonic.

Secondly, the important part of the second line is set(i for i in a if a.count(i) > 1), which just creates a new list containing only the duplicates from a (i.e. [1, 2, 3, 2, 3] becomes [2, 3, 2, 3] and then applies set to it, which converts [2, 3, 2, 3] into {2, 3} (which is a set object).

In case you're wondering what map(str, ...) is for, it's so that you can print each of the elements inside your new set (e.g. {2, 3}).

I am learnin python on a course and haven't known that yet. But it look pretty fine and easy. Thank you anyway. — pookeeshtron, Jul 05 '16 at 08:30
@AntonL. I've added an explanation to help you understand everything that's going on :) — sidney, Jul 05 '16 at 08:37

score 1 · Answer 2 · answered Jul 05 '16 at 08:32

1

You can use built-in lib collections to count list items and filter it by a required condition.

import collections

ints = map(int, input().split())
count = collections.Counter(ints)
print filter(lambda x: count[x] > 1, count)

answered Jul 05 '16 at 08:32

I159

29,741
31
97
132

Can't delete not last single object

2 Answers2