[R-sig-Geo] Intersect shapefiles

[John Wasige]

Thanks so much

On Thu, Feb 18, 2016 at 3:23 PM, chris english <
englishchristophera at gmail.com> wrote:

> 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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-- 
John Wasige
"There are no REGRATES in LIFE, just lessons (Jennifer Aniston)”

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