Re: GIS Distance from Point to Geometry Collection

Got it.  So what you want to do is a list comprehension over the geometry object, which should give you individual geometries is what it sounds like.  Then you can calculate distance() from each of these.  Something like this?

interesting_point = Point(x, y)

collection = result.geom

min_dist = min([g.distance(interesting_point) for g in collection])

or for every geometrycollection in a queryset:

result = MyModel.objects.all()

min_dist = min([min([g.distance(interesting_point) for g in coll]) for coll in result])

Brute force and thus a bit slow, but it should work if I understand you correctly...

-- Jeff

On Tue, Jan 31, 2012 at 8:45 PM, Alex Kopp <loaferdtd@gmail.com> wrote:

Here's a more concrete example, say I am storing shapes of all countries. Now, the US can't be stored in one polygon (we have hawaii and alaska), therefore I have to store the many polygons in one geometrycollection.

Now, say I have another point on the map, I would like to know how ar it is from ANY of the polygons...

On Tue, Jan 31, 2012 at 8:41 PM, Alex Kopp <loaferdtd@gmail.com> wrote:

Perhaps I didn't explain it well, Jeff. I am just trying to get the smallest distance from one point to any of the points, lines, or polygons inside of a queryset. The data I am receiving from the queryset is a geometrycollection already... That is how it is being stored in the database.

On Tue, Jan 31, 2012 at 8:36 PM, Jeff Heard <jefferson.r.heard@gmail.com> wrote:

You should be able to create a geometrycollection object from a queryset (you may have to use a list comprehension for this), then calculate the centroid and take the distance from that. Taking the distance from the edge should only be a little more
Complicated.  Check the django GEOS API docs For complete details

On Jan 31, 2012, at 6:36 PM, Loafer <loaferdtd@gmail.com> wrote:

> I have a model that currently stores a Geographic Point (Using Django
> GIS (GeoDjango)) and another model that has a field to store a
> geometry collection (A collection of polygons, lines, and or points).
>
> I am trying to find the distance from the point to any one of the
> shapes in the geometry collection. Apparently the distance function
> only works on single shapes, not a collection. Are there any
> workarounds to this?
>
> Any help is appreciated.
>
> Thanks.
>
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