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Generate a vector of names of intersecting polgons

2 messages · Steven Ranney, Robert J. Hijmans

Original
Steven Ranney
# 
All -

As a disclaimer, I admit that I am relatively new to spatial data
manipulation with R.  I am familiar with some of the more basic functions
and packages but need some guidance.

What I want to do:

I have two .shp files, shpA and shpB, both of which contain many polygons.
I would like to overlay shpA on shpB and get a vector of the polygon names
in shpB that intersect with polygons in shpA.  In a perfect world, I would
then be able to join the vector of names to each polygon in shpA as a new
attribute.

I tried using over() but over() didn't like the fact that both of my .shp
files were SpatialPolygonsDataFrames.

Is there a simple way to do this?  Can anyone offer some advice?

Thanks -

SR
Steven H. Ranney
Robert J. Hijmans
# 
Steven, I believe you can use something like the below

library(raster)
# example data (p, d)
p <- shapefile(system.file("external/lux.shp", package="raster"))
r <- raster(p)
values(r) <- 1:ncell(r)
d <- as(r, 'SpatialPolygonsDataFrame')

# approach 1
x <- intersect(p, d)

# approach 2
y <- union(p,d)
y <- y[!is.na(y$ID_1), ])

The approach to take depends on the case (does B fall entirely within A?)
On Mon, Oct 27, 2014 at 5:43 PM, Steven Ranney <steven.ranney at gmail.com> wrote: