CODEWITHSUNDEEP
djangopolygongeodjango
Du D.
Du D.

Reputation: 5310

How to expand or reduce a polygon with geodjango?

I got a model with field using the gis polygon field.

boundary = models.PolygonField()

As the requirement I need to allow the user to provide offset/tolerance value. How do I expand or shrink this polygon without doing the math myself?

Thanks!

Upvotes: 2

Views: 927

Answers (1)

e4c5
e4c5

Reputation: 53734

I do believe Geometry.buffer is what you are looking for.

from django.contrib.gis.geos import Polygon

poly = Polygon.from_bbox((0, 0, 5, 5))
poly.extent # (0.0, 0.0, 5.0, 5.0)
p2 = poly.buffer(1)
p2.extent #(-1.0, -1.0, 6.0, 6.0)

if you want to shrink it, use a negative value in the call to buffer

Upvotes: 5

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