splancs (version 2.01-45)

Fhat: F nearest neighbour distribution function

Description

Calculates an estimate of the F nearest neighbour distribution function

Usage

Fhat(pts1,pts2,s)

Value

A vector of the same length as s, containing the value of Fhat at the distances in s.

Arguments

pts1

A points data set

pts2

A points data set

s

A vector of distances at which to evaluate Fhat

Details

The function Fhat(pts1,pts2,s) is defined as the proportion of members of a point set pts2 for which the distance to the nearest member of another points set pts1 is less than or equal to s.

References

Rowlingson, B. and Diggle, P. 1993 Splancs: spatial point pattern analysis code in S-Plus. Computers and Geosciences, 19, 627-655; the original sources can be accessed at: https://www.maths.lancs.ac.uk/~rowlings/Splancs/. See also Bivand, R. and Gebhardt, A. 2000 Implementing functions for spatial statistical analysis using the R language. Journal of Geographical Systems, 2, 307-317.

See Also

nndistF,Fzero

Examples

data(uganda)
plot(seq(20, 500, 20), Fhat(as.points(uganda), 
as.points(csr(uganda$poly, length(uganda$x))), seq(20, 500, 20)), 
type="l", xlab="distance", ylab="Estimated F")
plot(Ghat(as.points(uganda), seq(20, 500, 20)), Fhat(as.points(uganda), 
as.points(csr(uganda$poly, length(uganda$x))), seq(20, 500, 20)), 
type="l", xlab="Estimated G", ylab="Estimated F")
lines(c(0,1),c(0,1),lty=2)