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+---- Thread: [Python] Simple Python Question (/showthread.php?tid=4461911)
Simple Python Question - ๖ۣۜSolace - Sep 25, 2014
Hello HF,
I have a simple question about a simple operation in python.
I'm attempting to pass a function a list (variable a), and exclude all numbers that are less than my second variable which is given by the user ®.
Code
def threshold(a,x):
for i, val in enumerate(a):
if a[i] < x:
a.remove(a[i]);
return a;
r = int(raw_input("Enter a number to take the threshold of:"));
print threshold([0,1,2,3,4,5,6],r);Could anybody explain to me why my code doesn't work? (I don't have any formal learning with python, I'm taking Java questions from an old course and replicating them to teach myself.)
Thanks :)
* - tyguy - Sep 25, 2014
could be youre returning a table or some shit idk
* - K-On! - Sep 25, 2014
Use del a[i] instead of a.remove(a[i]))
.remove() removes an item based on the value you give it, not by the index.
* - MoonCakeRuler - Sep 25, 2014
(Sep 25, 2014 12:25 PM)K-On! Wrote: Use del a[i] instead of a.remove(a[i]))
.remove() removes an item based on the value you give it, not by the index.
He passed a[i] to remove(), so it still counts as a value. D:
To the OP, your code doesn't work because you're enumerating and removing items from the list at the same time. If we take an example argument of a list [0,1,2,3,4] and the second argument as 2, your iterator condition removes 0 from the list. BUT, then your list shifts by one position and becomes [1,2,3,4]. However, the iterator also increases the index and so, you don't get what you need as the 1 is now in 0th position while the index is shifted to 1.
A better way to do this is a list comprehension:
Code
return [i for i in a if i >= x]