[SciPy-user] efficient "inside polygon" test for an array??
David Warde-Farley
dwf at cs.toronto.edu
Mon Feb 4 13:44:44 EST 2008
On 4-Feb-08, at 11:15 AM, John Hunter wrote:
> On Feb 4, 2008 9:56 AM, Eric Emsellem <emsellem at obs.univ-lyon1.fr>
> wrote:
>> Hi
>>
>> I have a polygon (defined by 4 vertices) and I wish to have an
>> efficient way of
>> selecting the points which are inside this polygon.
>> So I would like something like:
>>
>> selection = pointsInPolygon(x,y,poly)
It seems your problem has already been addressed, but some very good
discussion of this problem (along with some 30-odd year old code, and
a more recent C implementation) can be found at
http://www.ecse.rpi.edu/Homepages/wrf/Research/Short_Notes/pnpoly.html
I wouldn't be surprised if nxutils uses the same algorithm.
David
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