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</style>Hi Martin -<br><br> Is it always better to have a single MultiPoly?
my naive thoughts are a) single polys are computationally faster, and b) the
raison'detre of Multipolys is the "hole" , which could never be in a product of
otherwise independent single polys.. <br><br> I admit this email is
off-the-cuff so there could be something I am not thinking about at all.. there
it is though.. option to combine ? never combine ? <br><br> very best
regards from Berkeley, California<br> -Brian<br><br><br>On Mon, 13 Apr 2015
09:42:40 -0700, Martin Davis <mtnclimb@gmail.com> wrote:<br><blockquote
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<div dir="ltr"><br><div class="gmail_extra"><br><div class="gmail_quote">On Mon,
Apr 13, 2015 at 12:59 AM, Sandro Santilli <span dir="ltr"><<a
href="mailto:strk@keybit.net" target="_blank">strk@keybit.net</a>></span>
wrote:<br><blockquote class="gmail_quote" style="margin: 0 0 0 .8ex;
border-left: 1px #ccc solid; padding-left: 1ex;"><span class="">On Fri, Apr 10,
2015 at 10:40:32AM -0700, Martin Davis wrote:<br> > re what is happening in
Shapely with relate on GeometryCollections:<br> ><br> > In fact,
homogeneous GeometryCollections of Points and LineStrings can be<br> >
trivially converted to MultiPoints and MultiLineStrings. Is is possible<br>
> that Shapely is doing this automatically?<br> ><br> > Handling
homogeneous GCs would be a nice enhancement for JTS &
GEOS....<br><br></span>There's actually a ST_CollectionHomogenize function in
PostGIS that<br> can be used to do just that.<br><br>
</blockquote>
<div>I'm starting to think about adding a "flatten" method to JTS that would do
all the heavy lifting to transform an arbitrary GeometryCollection into
something suitable for using with relate. In addition to converting homogenous
collections into the appropriate Multi-type, it would union all polygons to make
them into a valid MultiPolygon. </div>
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</blockquote>
<br><br><p><br> --<br>Brian M Hamlin<br> OSGeo California Chapter<br>
blog.light42.com<br></p>
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