selecting certain elements in a list - python

Question

I am looking to edit elements in a list bar one element - I am wondering how to do so? I am making one element go up, the one selected, and the others to go down. I have worked out how to do the first bit, just not the second. Here is my code so far

score = [70,60,80]
action = ["one person off", 2, 200]

def take_action(score, action):
    x = action[1]
    if action[0] = "one person off":
        score[x] += 30

I am looking for 80 to go to 110 and the others to go down by 10 each.

Any help would be greatly appreciated!

Do you mean to add an else: part to the if statement with score[x] -= 10 in it? — mkrieger1
– mkrieger1, Commented Nov 15, 2021 at 16:29
@mkrieger1 no, I want it to both happen, so want score[x] += 30 and the something underneath that would represent elements that are not score[x] going down by 10 - sorry new to stack overflow — Bryn Owen-Conway
– Bryn Owen-Conway, Commented Nov 15, 2021 at 16:32

Alain T. · Accepted Answer · 2021-11-15 16:37:07Z

1

You could implement the action as loop:

for i,s in enumerate(score):
    score[i] = s+30 if i == x else s-10

edited Nov 15, 2021 at 16:37

answered Nov 15, 2021 at 16:33

Alain T.

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1 Comment

Bryn Owen-Conway Over a year ago

thank you very much! this has worked spot on!

Kemp · Accepted Answer · 2021-11-16 10:00:32Z

0

You can use a list comprehension:

score = [value+30 if i==x else value-10 for i,value in enumerate(score)]

This will give you back a new list, with the xth element increased by 30 and the others decreased by 10.

In order to modify the list that was passed in (rather than creating a new local variable named score) you would need to perform the assignment slightly differently:

score[:] = [value+30 if i==x else value-10 for i,value in enumerate(score)]

edited Nov 16, 2021 at 10:00

answered Nov 15, 2021 at 16:33

Kemp

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3 Comments

Alain T. Over a year ago

This will not update the score variable passed as parameter because it creates a new list in a local variable (also named score).

Kemp Over a year ago

@AlainT. Ah, you're correct. I was assuming there was a return that wasn't shown, but that may be a bad assumption.

Alain T. Over a year ago

you could assign score[:] = ... instead and it would work.

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