Why an incorrect result when deleting values from the list during its crawl [duplicate]

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Remove unique values from list 3 responses

There is a piece of code:

def remitem(mylist): mylist2=mylist for item in mylist: if (mylist.count(item)==1): mylist2.remove(item) return mylist2 print remitem([5, 6, 7, 8, 9])

Please tell me why he returns [6,8], then the cycle goes through one list, and deletes it from another - according to logic, does it have to return []?

It's easier: result = filter (lambda x: mylist.count (x)> 1, mylist)
d = {} for item in mylist: if item in d: d [item] = False else: d [item] = True result = filter (lambda x: d [x], mylist)
Related question: What is the difference between two for loops: when deleting items while traversing a list

Accepted Answer · 2013-08-29T11:50:38

because it is the same list, because it is mutable (you can read more by searching the Internet for this word)

if you need a copy of this list - use the copy command or mylist2 = mylist [:]

is mylist2 = mylist - just creating a link to the same memory area?

Why an incorrect result when deleting values from the list during its crawl [duplicate]

Reported as a duplicate by jfs python Members with Signs Jan 24 '17 at 3:59 pm

1 answer 1

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Why an incorrect result when deleting values ​​from the list during its crawl [duplicate]

Reported as a duplicate by jfs python Members with Signs python can individually close questions labeled python as duplicates, and also re-open them if necessary. Jan 24 '17 at 3:59 pm

1 answer 1

More articles:

Why an incorrect result when deleting values from the list during its crawl [duplicate]

Reported as a duplicate by jfs python Members with Signs Jan 24 '17 at 3:59 pm