Example: you are looking for the minimum absolute value in a series of
integers. As soon as you encounter the first 0 it's unnecessary extra work
to check the remaining values, but the builtin min() will continue.
The solution is a minimum function that allows the user to specify a stop
value:
>>> from itertools import count, chain
>>> stopmin(chain(reversed(range(10)), count()), key=abs, stop=0)
0
How would you implement stopmin()?
Currently I raise an exception in the key function:
class Stop(Exception):
pass
def stopmin(items, key, stop):
"""
>>> def g():
... for i in reversed(range(10)):
... print(10*i)
... yield str(i)
>>> stopmin(g(), key=int, stop=5)
90
80
70
60
50
'5'
"""
def key2(value):
result = key(value)
if result <= stop:
raise Stop(value)
return result
try:
return min(items, key=key2)
except Stop as stop:
return stop.args[0]
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