Python: How to combine the results of for loop into one output?

Question

numbers = [1, 2, 3]

for number in numbers:
   number = number * 2 

#For the output I will get:
2
4
6

How do I modify my code so the results can be combined (eg. [2, 4, 6]) without using the print statement?

Solution 1

Use a list comprehension:

[num*2 for num in numbers]

---

>>> numbers = [1, 2, 3]
>>> [num*2 for num in numbers]
[2, 4, 6]
>>> 

Solution 2

Create new List type variable result and add values into it by list append() method.

Demo:

>>> numbers = [1, 2, 3]
>>> result = []
>>> for i in numbers:
...   result.append(i*2)
... 
>>> result
[2, 4, 6]
>>> 

Comments

[wallyk]

Do you mean you do not want to output the result? Only calculate it?

[abarnert]

I don't know what you mean "# For the output I will get: 2 4 6". There is no output here at all. And no effect; all you're doing each time through the loop is reassigning the loop variable number to a different value, which you then immediately forget.

[TigerhawkT3]

It sounds like you're confusing the Python interpreter's behavior of displaying returned values with the built-in print() function.