[R-sig-Geo] "Merge" shapefiles

[Tyler Frazier]

Not to belittle the spatial capabilities of R, but this sounds like a function that would be better addressed with PostgreSQL/postgis.  Integrating r & pgsql can be a good combination.

Sent from my iPhone

> On Nov 14, 2014, at 1:11 AM, Steven Ranney <steven.ranney at gmail.com> wrote:
> 
> All -
> 
> I am slowly learning more about spatial data in R.  However, I am still a
> relative neophyte.
> 
> What I want to do:
> 
> I have two shapefiles, shpA has ~401,000 individual polygons with
> attributes.  shpB is a subset of those polygons with different attribute
> data.  Even though shpB is a subset of those data, there may be multiple
> rows for a given polyon, thus giving shpB more total rows (~780,000).
> 
> Effectively, I want to merge these two shapefiles.  With two dataFrame
> objects in R, I would merge them like
> 
> merge(shpA, shpB, by = "APN_LABEL", all = TRUE)
> 
> but apparently, this doesn't work with shapefiles.  I have tried
> 
> merge(shpA at data, shpB at data, by = "APN_LABEL", all = TRUE)
> 
> which creates a dataFrame of the the two files but drops all of the spatial
> geometries.
> 
> I've looked into gUnion() as it seems like that may be what I'm looking
> for, but I get the following error:
> 
> tmp <- gUnion(shpA, shpB)
> Error in RGEOSBinTopoFunc(spgeom1, spgeom2, byid, id, drop_lower_td,
> "rgeos_union") :
>  std::bad_alloc
> 
> Ultimately, I want a shapeFile of all ~401,000 geometries in shpA that
> includes ALL of the attribute data from shpB that may exist in multiple
> rows for a given polygon.
> 
> Is this possible?  Is this simple?
> 
> Steven H. Ranney
> 
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> 
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