Find day of week from month and year

[John Machin]

Peter Hansen wrote:
> Carsten Haese wrote:
> 
>> On Fri, 2005-09-02 at 16:46, Laguna wrote:
>>
>>> def expiration(year, month):
>>>     weekday = calendar.weekday(year, month, 1)
>>>     table = [19, 18, 17, 16, 15, 21, 20]
>>>     return table[weekday]
>>>
>> This, of course, can be "optimized" into
>>
>> def expiration(year, month):
>>     return [19,18,17,16,15,21,20][calendar.weekday(year,month,1)]
>>
>> ;)
> 
> 
> True, but do you find that more readable?  If I saw that in code I was 
> maintaining I would likely rewrite it, probably to look a lot like the 
> first one (though likely with a more descriptive name than "table"... 
> maybe expirationTable?).
> 
> (And, if I were "optimizing", I would of course dispense with the 
> dynamic creation of the static table upon every execution of 
> expiration(), and move it outside the function.)
> 
> -Peter

An alternative:

def expiration(year, month):
     return 21 - (calendar.weekday(year,month,1) + 2) % 7