How to print lambda result ?
steve at holdenweb.com
Wed Jan 21 14:31:44 CET 2009
Because your print statement defines the lambda without calling it.
Barak, Ron wrote:
> Thanks Tino: your solutions without the lambda work nicely.
> What I still don't understand is why the print does not execute the lambda and prints the result, instead of printing the lambda's object description.
> -----Original Message-----
> From: Tino Wildenhain [mailto:tino at wildenhain.de]
> Sent: Tuesday, January 20, 2009 14:22
> To: Barak, Ron
> Cc: python-list at python.org
> Subject: Re: How to print lambda result ?
> Barak, Ron wrote:
>> Wanting to print the correct plural after numbers, I did the following:
>> for num in range(1,4):
>> string_ = "%d event%s" % (num,lambda num: num > 1 and "s" or "")
>> print string_
>> However, instead of getting the expected output:
>> 1 event
>> 2 events
>> 3 events
>> I get:
>> 1 event<function <lambda> at 0x00AFE670>
>> 2 event<function <lambda> at 0x00AFE670>
>> 3 event<function <lambda> at 0x00AFE6B0>
> lambda creates a function so this is the result you are seeing. You would need to call the function to get your result.
> (num,(lambda n: n >1 and "s" or "")(num))
> which is just a quite useless application of lambda :-)
> (num,num >1 and "s" or "")
> or even
> (num,"s" if num >1 else "")
> in python > 2.5
> or in python <3.0:
> (num,"s"*(num >1))
Steve Holden +1 571 484 6266 +1 800 494 3119
Holden Web LLC http://www.holdenweb.com/
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