Search a sequence for its minimum and stop as soon as the lowest possible value is found

[Peter Otten]

Wolfgang Maier wrote:

> On 1/6/2017 15:04, Peter Otten wrote:
>> 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()?
>>
> 
> How about:
> 
> def stopmin (iterable, key, stop):
>      def take_until ():
>          for e in iterable:
>              yield e
>              if key(e) <= stop:
>                  break
>      return min(take_until(), key=key)
> 
> ?

Clean and simple -- if it could be tweaked to invoke key() just once per 
item it would be perfect.