list

[frequency]

How can i multiply even numbers from a list?
I have this code

credit_card_sum=[] credit_card_int=[[b]5[/b],6,[b]7[/b],8] for i in range(len(credit_card_int)): credit_card_sum.append(credit_card_int[i]) i=i+1 print (credit_card_sum)

I want to multiply 5 and 7 by 2 and append them to a list!

[j.crater]

Please put your code in Python code tags, it is required for the code to be displayed in a readable manner. You can find help here.

I am not sure I understood you right. Do you want to multiply (by 2) all the integers with an even index in a list?
So for your example, the result should be:

credit_card_int=[5,6,7,8] credit_card_sum=[10, 14]

Is that right? If not please write an example of input and output you want.

[frequency]

For example

 credit_card_int=[5,6,7,8] 

For this list. (happens to be 4 items) i want the even numbers from the i to be multiplied by 2. For example. Since for starts from 0 its cound, 5 and 7 will be multiplied because with the for use 0 and 3 are even numbers. So the 0(first item) and the 3rd item will be multiplied

[stullis]

Oh! You want the numbers at the even indexes to be doubled. I see it now. Slice the list and then double the numbers with a function or use a list comprehension:

credit_card_int=[5,6,7,8] x = [num * 2 for num in credit_card_int[::2]]

[j.crater]

There are several ways to accomplish this. You could go with:

for index, number in enumerate(credit_card_int) if not(index % 2): credit_card_sum.append(number*2)

If you don't know how enumerate works, check a reference online, for example here.
Also read on modulus operator (%) if you are not familiar with it.

[j.crater]

Suggestion by @stullis to slice the list is excellent, I wish I had thought of it on my own :)
However, as a beginner, I would not go with a list comprehension just yet. Otherwise it's a very nice, and efficient, solution ;)

[frequency]

Thank you all for your posts! It works very nice. But how can i make it so when it makes the calculations to get the indexed result and remove the number that made the calculation and appanend the new one. So i dont have 2 lists but one.

if a list has 3 items. Lets say

 list=[5,0,2] 

when the enumerate fuction finishes its job,i must have

list=[10,0,4]

. Now with this current code if i have

list=[5,0,2]

i get the result appended to an other list with the following items in it

 [10,4] 

. Summarising. How can i make the function to append the result of the calculation to the indexed number,keeping the other unchanged numbers in their position?
Thank you!

[stullis]

Using the code @j.crater provided, you can index the original list and change the contents at that index:

for index, number in enumerate(credit_card_int) if not(index % 2): credit_card_init[index] = number*2

[frequency]

Thank you! May i ask how can i split the item from a list that is a 2digit number and make a sum out of those? For example. If item[0] is 15 i must replace 15 with the sum of the 2 digits.So 6! I think i have to make them str ,append them to a list,split them and see whats next

[j.crater]

Do you mean this?
Was the offered solution not alright?