4 · Build useful programs · 9 MIN

Select matching items

Filtering keeps items that meet a rule.

A list comprehension builds a new list. [n for n in values if condition] keeps matching items in order. The % operator calculates a remainder. Filtering n values takes O(n) time and up to O(n) extra space.

A sieve keeps only the items that fit a rule.

Read the example

scores = [30, 60, 90]
passed = [n for n in scores if n >= 60]
print(passed)

[60, 90]

Your challenge

Return a new list containing only the even numbers from input, preserving order.

Common trap

Use == to compare values; = assigns a value.