[Python-Dev] Any reason that any()/all() do not take a predicateargument? (original) (raw)

"Martin v. Löwis" martin at v.loewis.de
Sat Apr 15 22:16:14 CEST 2006

Bill Janssen wrote:

Yeah, but you can't do more complicated expressions that way, like

any(lambda x: x[3] == "thiskey")

Not /quite/ sure what this is intended to mean, but most likely, you meant

   any(x[3]=="thiskey" for x in seq)

I think it makes a lot of sense for any and all to take optional predicate function arguments.

I don't believe that adds expressiveness: you can always formulate this with a generator expression - apparently, those are of the "read-only" nature, i.e. difficult to formulate (assuming you have no difficulties to read above term).

I suppose

(len([x for x in SEQ if PRED(x)]) > 0) will suffice for now. Obvious enough, Martin?

It's simpler written as

  any(PRED(x) for x in SEQ)

or

  any(True for x in SEQ if PRED(x))

if you want

Using any() has the advantage over len() that the any() code stops at the first value that becomes true, whereas the len code ill compute them all.

Regards, Martin

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