[Numpy-discussion] how to tell if a point is inside a polygon

Pierre GM pgmdevlist@gmail....
Mon Oct 13 18:46:01 CDT 2008


> 2008/10/13 Mathew Yeates <myeates@jpl.nasa.gov>
>
> > Is there a routine in scipy for telling whether  a point is inside a
> > convex 4 sided polygon?

Mathew,
You could use OGR (www.gdal.org)

Example
-------------
import osgeo.ogr as ogr

vert = [(0,0),(0,1),(1,1),(1,0)]
listvert = [" %s %s" % (x,y) for (x,y) in vert]
listvert.append(listvert[0])
geo = ogr.CreateGeometryFromWkt("POLYGON ((%s))" % ','.join(listvert))

querypoint = (0.5, 0.5)
qpt = ogr.CreateGeometryFromWkt("POINT(%s %s)" % querypoint)

assert geo.Contains(qpt)

querypoint = (0.5, 1.5)
qpt = ogr.CreateGeometryFromWkt("POINT(%s %s)" % querypoint)

assert not geo.Contains(qpt)



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