Re: DateTime->season?

On Jan 29, 2008, at 03:19, Zefram wrote:

> David E. Wheeler wrote:
>>       return $date lt '03-21' ? 'winter'
>>            : $date lt '06-21' ? 'spring'
>
> Northern hemisphere chauvinism.

It was a very limited need, in Virginia, so good enough.

> Aside from the hemisphere issue, the code is also wrong for tropical
> latitudes, where the four-season system doesn't apply.  If you're  
> trying
> to answer a user's question of "what season is it?" then you need a  
> lot
> more flexibility.  Even within the four-season system, people draw the
> boundaries in different places.  That's inevitable when trying to  
> impose
> sharp distinctions on a system that actually has a fuzzy continuum.

Yes, I realized some time after posting this that my implementation  
was very naive, and not likely to be usable outside a very narrow  
geographical area. But as I said, the immediate need was within that  
area, so for purposes of a quick hack, it works fine. :-)

> Sounds like you're looking for the equinox and solstice dates.  I  
> don't
> see any CPAN module providing this, on search.cpan.org.  I guess
> that makes it your job to write one.  Ideally you'd want to work from
> Astronomical Algorithms <http://www.willbell.com/math/mc1.htm>.   
> Google
> for "equinox calculation" to find several lower-precision algorithms  
> in
> various programming languages.

Might be an interesting thing to add.

Thanks for the feedback, folks,

David