[SciPy-user] efficient "inside polygon" test for an array??
Robert Kern
robert.kern at gmail.com
Mon Feb 4 14:12:38 EST 2008
David Warde-Farley wrote:
> 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.
It does.
--
Robert Kern
"I have come to believe that the whole world is an enigma, a harmless enigma
that is made terrible by our own mad attempt to interpret it as though it had
an underlying truth."
-- Umberto Eco
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