if does not evaluate

Jim Newton jimka at rdrop.com
Fri Jun 11 15:51:15 CEST 2004


sorry, i do not understand.  The python syntax is a bit
difficult for me.

if i have a list x and a function f how do i know if
there is an element of x on which f returns something
other than False?

-jim


Peter Otten wrote:
> Jim Newton wrote:
> 
> 
>>By the way, how do you find out in Python if there is
>>a member of a list that matches a condition?  It is something
>>i often and never know the best way to do it?  I can
>>use a list compression to find ALL the matches, but what
>>if i only want to know whether or not there is a match?
> 
> 
> Generator expressions will solve that, I think
> 
> "Mary" in (person.name for person in people)
> 
> In the meantime:
> 
> 
>>>>class Person:
> 
> ...     def __init__(self, name):
> ...             self.name = name
> ...
> 
>>>>people = map(Person, "Jim Bob Mary Sue".split())
>>>>
>>>>def attrgetter(name):
> 
> ...     return lambda o: getattr(o, name)
> ...
> 
>>>>import itertools
>>>>"Mary" in itertools.imap(attrgetter("name"), people)
> 
> True
> 
> No big deal.
> 
> Peter
> 




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