How do I create a numerical list, and then replace the odd numbers in the list with first even numbers higher than them?

Question

For example: ([3,85,44,71,9,5]) would return ([4,86,44,72,10,6])

The user inputs the information, so would I have to create an empty list?

Lots of help would be appreciated

Thank you!

score 3 · Answer 1 · answered Jun 11 '14 at 03:31

3

list1 = [3,85,44,71,9,5]
list2 = [x + (x%2) for x in list1]

noting that x%2 is 1 for odd numbers and 0 for even numbers.

answered Jun 11 '14 at 03:31

nneonneo

score 2 · Answer 2 · edited May 23 '17 at 12:05

2

Using lambda and ternary operator:

list1 = [3,85,44,71,9,5]
map(lambda x: x if x%2==0 else x+1, list1) 
[4, 86, 44, 72, 10, 6]

edited May 23 '17 at 12:05

Community

answered Jun 11 '14 at 03:29

b.b3rn4rd

tips: (1) don't name variables the same as built-ins (`list` is a built-in function), (2) use list comprehensions instead of `map` where possible because list comprehensions are faster and more readable. – nneonneo Jun 11 '14 at 03:35

score 0 · Answer 3 · answered Jun 11 '14 at 03:27

0

list = []
num = 0
while (num != -1):
   num = input("Enter number; enter -1 to end: ")
   if (num != -1):
      list.append(num+1)

answered Jun 11 '14 at 03:27

Shoikana

This describes how to make a list from user input, but not how to increment the odd numbers. – nneonneo Jun 11 '14 at 03:35
That's true.. doesn't the original question state that the user inputs the information? – Shoikana Jun 11 '14 at 03:37
It's not clear _how_ the user inputs the information. Lacking that, it's hard to recommend a particular approach. (Your code is reasonable but not too Pythonic; I would recommend just using an infinite loop and a `break`, and losing the parentheses around the `while` and `if` conditions). – nneonneo Jun 11 '14 at 03:40

score 0 · Answer 4 · answered Jun 11 '14 at 04:02

Use modulo:

arr = [3,85,44,71,9,5]
arr = [item + item%2 for item in arr]

This runs as:

>>> arr = [3,85,44,71,9,5]
>>> arr = [item + item%2 for item in arr]
>>> arr
[4, 86, 44, 72, 10, 6]
>>>

% works as such:

>>> 9%2 #Gives 1, because 9/2 is 4 remainder 1
1
>>> 10%2 #Gives 0, because 10/2 is 5 remainder 0
0
>>>

4 Answers4