return the number that occur only once in a array python

Question

I have an array [1,2,3,4,5,6,1,2,3,4] and I would like to return 5, 6.

If I use set(my_array) I get 1,2,3,4,5,6. Is there a pythonic way to do this. Thanks.

Any help is much appreciated.

There are so many questions about counting occurrences (and indeed, ways to do so in Python) that I feel like this question was barely researched. It's almost certainly a duplicate. — Two-Bit Alchemist
– Two-Bit Alchemist, Commented Jun 8, 2016 at 15:32

Jeremy · Accepted Answer · 2016-06-08 19:31:58Z

2

#List of data which has every item repeated except for 5 and 6
lst= [1,2,3,4,5,6,1,2,3,4]

#This list comprehension prints a value in the list if the value only occurs once.
print [x for x in lst if lst.count(x)==1]
#Output
[5, 6]

edited Jun 8, 2016 at 19:31

answered Jun 8, 2016 at 15:47

Jeremy

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1 Comment

Jeremy Over a year ago

@ppperry I added a couple of comments to explain it more. I thought it was a fairly basic list comprehension.

Burhan Khalid · Accepted Answer · 2016-06-08 20:28:36Z

1

You can use the appropriately named filter method:

>>> i = [1,2,3,4,5,6,1,2,3,4]
>>> filter(lambda x: i.count(x) == 1, i)
[5, 6]

answered Jun 8, 2016 at 20:28

Burhan Khalid

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