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!
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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.
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
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]]
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.
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 ;)
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!
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
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