replacing a variable in a list using a for-loop?

Question

I am trying to replace the value 11 with the value of 1.

What am I doing wrong?

I want it to be:

[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 10, 10]

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score 1 · Answer 1 · answered May 02 '22 at 20:40

1

You could do this with a list comprehension:

cards = [11, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 10, 10]
[1 if i==11 else i for i in cards]

Output:

[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 10, 10]

answered May 02 '22 at 20:40

Nin17

score 0 · Answer 2 · answered May 02 '22 at 20:39

0

for i in range(len(cards)):
    if cards[i]==11:
        cards[i]=1

answered May 02 '22 at 20:39

Amir Sabzehparvar

7

this is unidiomatic. You should use `enumerate` here. – juanpa.arrivillaga May 02 '22 at 20:39

var211 · Answer 3 · 2022-05-02T20:47:38.347

0

In your exampe i is an item in list, not an index:

cards = [11, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 10, 10]

for i, val in enumerate(cards):
    if val == 11:
        cards[i] = 1


print(cards)

edited May 02 '22 at 20:47

answered May 02 '22 at 20:39

var211

1

this is unidiomatic, you should use `enumerate` here – juanpa.arrivillaga May 02 '22 at 20:40
Why? You don't need a value in that example to use `enumerate` – var211 May 02 '22 at 20:40
1

You do, you are using `cards[i]` – juanpa.arrivillaga May 02 '22 at 20:41
1

Man, there is no such a word as `unidiomatic` )) - https://dictionary.cambridge.org/spellcheck/english/?q=unidiomatic – var211 May 02 '22 at 20:42
You should use: `not idiomatic` – var211 May 02 '22 at 20:43
No, you should not use not idiomatic code ... – Matthias May 02 '22 at 20:46
@var211 https://www.collinsdictionary.com/dictionary/english/unidiomatic shh – Nin17 May 02 '22 at 20:46
Just kidding, I agree and changed my code. You right. – var211 May 02 '22 at 20:48

MATOS · Answer 4 · 2022-05-03T10:52:51.240

-1

my_list = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 10, 11]
i = 0
while i < len(my_list):
    if my_list[i] == 11:
        my_list[i] = 1
    i += 1

edited May 03 '22 at 10:52

answered May 02 '22 at 20:40

MATOS

this is not correct, it should be ```for i in range(len(list)):``` or ```for i, _ in enumerate(list):``` also, you shouldn't overwrite the builtin python ```list``` – Nin17 May 02 '22 at 20:43
Don't use `list` as a name for a variable. You're overwriting the built-in [`list`](https://docs.python.org/3/library/functions.html#func-list). And why do you use `else` if you just continue? – Matthias May 02 '22 at 20:43
else was just to show what happens if that isn't true, the listname was quick thinking – MATOS May 02 '22 at 20:47
@Nin17 There is nothing wrong with ```for i in my_list``` it all works just the same – MATOS May 02 '22 at 20:48
@MATOS no it doesn't try it. Put ```print(list)``` after that and you get ```[1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 10, 10, 11]``` note the 11 is still there. If you change the values you can easily get an ```IndexError: list index out of range``` error which you're only avoiding because ```len(list)>max(list)``` – Nin17 May 02 '22 at 20:48
yes very sorry about that, forgot that it skipped those, I added a sample while loop for another example of choice – MATOS May 02 '22 at 20:58
well apart from it changing 11 to 10 instead of 1 it works now – Nin17 May 02 '22 at 21:31
Still not a good answer, but at least working. – Matthias May 03 '22 at 07:08

4 Answers4