[R] Spatial join between two datasets using x and y co-ordinates

From: Andrew McFadden <Andrew.McFadden_at_maf.govt.nz>
Date: Wed, 07 May 2008 09:22:36 +1200


Hi R users

I am trying to create a spatial join between two datasets.

The first data set is large and contains descriptive data including x and y co-ordinates.

The second dataset is small and has been selected spatially. The only data contained within the second dataset is the x and y coordinates only i.e. no descriptive data.

The aim of a join made between the two datasets is to select those points (and hence all the descriptive data) from dataset one that has the same x and y co-ordinates as dataset two.

x1<-c(1824615,1823650,1821910)
y1<-c(5980732,5983220,5990931)
descript<-c("cat", "dog", "horse")
dat1<-data.frame(x1,y1,descript)

x2<-c(1824615,1823650)
y2<-c(5980732,5983220)
dat2<-data.frame(x2,y2)

dat1
dat2

The aim of the join is to produce:

       x1      y1 descript
1 1824615 5980732      cat
2 1823650 5983220      dog

And therefore limit the data in dataset 1 to that which has the same x and y co-ordinates as dataset 2.

Any suggestions?

Regards

Andy

Andrew McFadden MVS BVSc
Incursion Investigator
Investigation & Diagnostic Centres - Wallaceville Biosecurity New Zealand Ministry of Agriculture and Forestry

Phone 04 894 5600 Fax 04 894 4973 Mobile 029 894 5611 Postal address: Investigation and Diagnostic Centre- Wallaceville Box 40742 Ward St Upper Hutt

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