# Example for the use of the K2-index
# developed under R-version 2.5.1

# Katja Schiffers, Frank M. Schurr, Katja Tielboerger, 
# Carsten Urbach, Kirk Moloney, and Florian Jeltsch 

library(spatstat)
library(spatial)

source("Funktionen/K2.R")


# generating pattern with positive autocorrelation on scale 0.9 with intensity 0.5 
# and negative autocorrelation on scale 0.6 with intensity 0.95

twoscalepp <- function(n, attsc=attsc, attint=attint, repsc=repsc, repint=repint)
  {

    loc <- matrix(NA, nrow=n, ncol=2)
    
    set <- FALSE
    
    loc[1,1]<- runif(1, min=0, max=20)
    loc[1,2]<- runif(1, min=0, max=20)
    
    N <- 1
    att <- runif(1, min=0, max=1)
    rep <- runif(1, min=0, max=1)
    
    while(N < n)  {
      x <- runif(1, min=0, max=20)
      y <- runif(1, min=0, max=20)
      
      
      for(i in 1:N){
        if(set==FALSE){
          dist <- sqrt(((loc[i,1]-x)^2)+((loc[i,2]-y)^2))
          
          if((dist < attsc) && (att < attint)) set <- TRUE
          if((dist > attsc) && (att > attint)) set <- TRUE
        }
      }
      for(j in 1:N){
        dist <- sqrt(((loc[j,1]-x)^2)+((loc[j,2]-y)^2))
        
        if((dist < repsc) && (rep < repint)) set <- FALSE
      }
      
      if(set==TRUE){
        att <- runif(1, min=0, max=1)
        rep <- runif(1, min=0, max=1)
        
        
        N <- N+1
        loc[N,1] <- x
        loc[N,2] <- y
        cat(N, " ")
        if(N%%10==0) cat("\n")
        set <- FALSE
      }
      
    }
    pp <- ppp(loc[,1], loc[,2], window=owin(c(0,20), c(0,20)))
    return(pp) 
  }


two <- twoscalepp(150, attsc=0.9, attint=0.95, repsc=0.6, repint=0.75)
plot(two, pch=20, cex=0.8, xlab="", ylab="")


# analysing pattern with Ripley's K-function and plotting the L-function

twoK <- envelope(two, fun=Kest)
plot(twoK, sqrt(./pi)-r ~ r, xlab="scale(r)",ylab="L(r)", main="Ripley's K")

# analysing pattern with pair correlation function with kernel width parameter 'stoyan' = 0.15

twoPCF <- envelope(two, fun=pcf.ppp, stoyan=0.15)
plot(twoPCF, xlab="scale(r)",  ylab="g(r)", main="Pair correlation function")

# analysing pattern with K2-index with kernel width parameter 'stoyan' = 0.15

twoK2 <- K2(two, nsim=99, stoyan=0.15)
plot(twoK2, main="K2-index", xlab="scale(r)", ylab="K2(r)")