Removing element in a list

Question

list = [0, 1, 2, 8, 2, 9, 2]

Is there a way to remove the element 2, exactly one time?

So you will get:

list = [0, 1, 2, 8, 9, 2]

I tried to work with index() but I didn't found it.

It can be a RANDOM 2.

So I can't use remove() or pop() because it will not remove the number 2 on a random position.

Your intended output has the second `2` being removed, what criteria should decide which number is removed? — SuperBiasedMan, Nov 17 '15 at 10:15
It deletes a random number '2' in the list. The output can be something else because there are three of them. — Victor, Nov 17 '15 at 10:17
if the list can be random, why can't you use `remove`? It removes the first occurrence... — Pynchia, Nov 17 '15 at 10:22
I'm sorry but your question is a bit confusing. Are you always going to remove a 2, or can it be a different number? — Bridgekeeper, Nov 17 '15 at 10:22

score 6 · Answer 1 · answered Nov 17 '15 at 10:11

6

This works

list.remove(2)

L.remove(value) -- remove first occurrence of value.

Raises ValueError if the value is not present.

answered Nov 17 '15 at 10:11

Bridgekeeper

the OP says he doesn't want/cannot use `remove` – Pynchia Nov 17 '15 at 10:25
@Pynchia: The OP _believes_ he can't use `remove`. – Matthias Nov 17 '15 at 10:28
1

ahahahahaha, yes, that is what I have told him, he can, since the list is randomly popoulated. Anyhow, better leave this awful question to somebody else. BTW I've removed my answer and upvoted this one – Pynchia Nov 17 '15 at 10:30
Your solution deletes the first element found. I need to delete a RANDOM one. – Victor Nov 17 '15 at 10:36
1

@Victor You never told that it should be a random 2 in your question. – Bridgekeeper Nov 17 '15 at 10:38
@Matthias Funny business. – Bridgekeeper Nov 17 '15 at 11:11

score 1 · Answer 2 · answered Nov 17 '15 at 10:16

1

Use del or pop

For example,

del list[2]

or

list.pop(2)

The difference between del and pop is that

del is overloaded.

for example, del a[1:3] means deletion of elements 1 and 3

answered Nov 17 '15 at 10:16

신형준

score 1 · Accepted Answer · edited May 23 '17 at 11:44

1

To randomly remove occurrence of 2

Notes:

we create a list of indexes of the number 2 i.e. [i for i, j in enumerate(lst) if j == 2]
Using random module choice method to get one index randomly from the index list
list pop method or remove method it's up to your choice

Code:

import random
lst = [0, 1, 2, 8, 2, 9, 2]
lst.pop(random.choice([i for i, j in enumerate(lst) if j == 2]))
print lst

output:

[0, 1, 8, 2, 9, 2]

edited May 23 '17 at 11:44

Community

answered Nov 17 '15 at 10:27

The6thSense

score 0 · Answer 4 · answered Nov 17 '15 at 10:10

0

Note that you're shadowing the built-in list. Apart from that index works just fine:

>>> li = [0, 1, 2, 8, 2, 9, 2]
>>> li.pop(li.index(2))
2
>>> li
[0, 1, 8, 2, 9, 2]

answered Nov 17 '15 at 10:10

Sebastian Wozny

4 Answers4