[R-sig-Geo] Intersect shapefiles

[chris english]

John,

As Loic suggests, rgeos::gIntersection will get you there. Look closely at
his naming of objects and your example code using spTransform. With his
approach, each object has its own name; whereas your approach overwrites
Rain_poly_merge the second and third time and the final object (third) is
the 2008 maize yield. So read your shapefiles into differently named
objects and use Loic's approach.

Chris

On Thu, Feb 18, 2016 at 1:58 PM, A. Marcia BARBOSA <barbosa at uevora.pt>
wrote:

> Check out also function joinPolys in the PBSmapping package
> (http://www.inside-r.org/packages/cran/pbsmapping/docs/joinPolys)
>
>
> - - -
> A. Márcia BARBOSA, post-doctoral fellow
> CIBIO/InBIO - University of Évora (Portugal)
> http://modtools.wordpress.com/barbosa
>
>
>
> 2016-02-18 10:04 GMT+00:00 Loïc Dutrieux <loic.dutrieux at wur.nl>:
>
> > Hi,
> >
> > Have you tried gIntersection from the rgeos package.
> >
> > Given 3 SpatialPolygon* objects you can probably do something like:
> >
> > sp12 <- gIntersection(sp1, sp2)
> > sp123 <- gIntersection(sp12, sp3)
> >
> > Cheers,
> > Loïc
> >
> >
> > On 02/18/2016 10:25 AM, John Wasige wrote:
> >
> >> ​Dear all,
> >>
> >> I have three shapefiles that I want to intersect. Any body with an idea
> on
> >> how to do the intersection? Shapefiles below;
> >> library(rgdal)
> >> library(rgeos)
> >> library(maptools)
> >> library(sp)
> >> ###shape1
> >> Rain_poly_merge <- readOGR(dsn="G:/EPIC_CUP/Rain_poly_merge.shp",
> >> layer="Rain_poly_merge")
> >> Rain_poly_merge <- spTransform(Rain_poly_merge, CRS("+init=epsg:4326"))
> >>
> >> ###shape2
> >> Rain_poly_merge <-
> readOGR(dsn="G:/EPIC_CUP/yield_maize_average2002.shp",
> >> layer="Rain_poly_merge")
> >> Rain_poly_merge <- spTransform(Rain_poly_merge, CRS("+init=epsg:4326"))
> >>
> >> ###shape3
> >> Rain_poly_merge <-
> readOGR(dsn="G:/EPIC_CUP/yield_maize_average2008.shp",
> >> layer="Rain_poly_merge")
> >> Rain_poly_merge <- spTransform(Rain_poly_merge, CRS("+init=epsg:4326"))
> >>
> >>         [[alternative HTML version deleted]]
> >>
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> >>
> >>
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