def double( number )
return 2 * number
number_list = [ 1, 4, -2 ]
# easier than list comprehension
new_double_list = map( double , number_list )
def odd(n)
return n % 2
...
>>> li = [1, 2, 3, 5, 9, 10, 256, −3]
>>> filter(odd, li)
[1, 3, 5, 9, −3]
>>> [e for e in li if odd(e)]
>>> filteredList = []
>>> for n in li:
... if odd(n):
... filteredList.append(n)
...
>>> filteredList
[1, 3, 5, 9, −3]
files = os.listdir(path)
test = re.compile("test\.py$", re.IGNORECASE)
files = filter(test.search, files)