[R] Distances between two datasets of x and y co-ordinates

From: Andrew McFadden <Andrew.McFadden_at_maf.govt.nz>
Date: Thu, 13 Mar 2008 09:47:27 +1300

Hi all

I am trying to determine the distances between two datasets of x and y points. The number of points in dataset One is very small i.e. perhaps 5-10. The number of points in dataset Two is likely to be very large i.e. 20,000-30,000. My initial approach was to append the first dataset to the second and then carry out the calculation:

dists <- as.matrix(dist(gis data from 2 * datasets))

However, the memory of the computer is not sufficient. A lot of calculations carried out in this situation are unnecessary as I only want approx 5 * 20,000 calculations versus 20,000 *20,000.

x <- c(2660156,2663703,2658165,2659303,2661531,2660914)
y <- c(6476767,6475013,6475487,6479659,6477004,6476388)
data2<-cbind(x,y)

x <- c(266500,2611111)
y <- c(6478767,6485013)
data1<-cbind(x,y)

Any suggestions on how to do this would be appreciated.

Regards

Andrew

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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