Question

I have been working my way through the tutorials on learnpython.org and up to this point have found everything relatively straightforward.

When I came to the question about list comprehension I have become stuck. I have a grasp of how it works. Below is the question that is asked:

Using a list comprehension, create a new list called “newlist” out of
the list “numbers”, which contains only the positive numbers from the
list, as integers.

And the code supplied:

numbers = [34.6, -203.4, 44.9, 68.3, -12.2, 44.6, 12.7]
newlist = []

print newlist

My answer to this question was as follows:

newlist = [x for x in numbers if x > 0]

This returns the correct numbers from the array, but with each item to about 15 dp. How do I get just the integers and not all the decimal places.

For example that answer that is expected is:

[34, 44, 68, 44, 12]

However I end up with:

[34.600000000000001, 44.899999999999999, 68.299999999999997, 44.600000000000001, 12.699999999999999]

If anyone is able to shed some light as to where I am going wrong then it would be much appreciated.

Cheers,

Jamie

Answer 1

newlist = [int(x) for x in numbers if x > 0]

This rounds numbers toward zero. Positive numbers will be rounded down and negative numbers will be rounded up. If you want to round to the nearest integer:

newlist = [round(x) for x in numbers if x > 0]