library(KernSmooth)
library(spatgraphs)
linbin2D <- get("linbin2D", envir=environment(bkde2D))
Npt<-300
x<-y<-rep(0,Npt)
r<-10
for(i in 1:Npt){
t<-runif(1)*2*pi/1
r2<-r*(sin(t*200)+10)+rnorm(1)*0.1
x[i]<-r2*cos(t)
y[i]<-r2*sin(t)
}
pp2d<-list(x=x,y=y,n=length(x),window=list(x=range(c(x,y)),y=range(c(x,y))))
R<-0.2
k<-1
e1<-spatgraph(pp2d,"geometric",par=R)
e2<-spatgraph(pp2d,"knn",par=k)
e3<-spatgraph(pp2d,"MST")
A<-spatcluster(e2)
plot(pp2d, main="Minimum spanning tree")
plot(e3,pp2d)
f1 <- bkde2D(cbind(x, y) ,bandwidth=c(10,10),gridsize=c(101,101))
contour(f1$x1, f1$x2, f1$fhat)
persp(f1$fhat)
library(rgl)
xy<-expand.grid(f1$x1,f1$x2)
plot3d(xy[,1],xy[,2],f1$fhat)
x<-cbind(x,y)
gridsize = c(51L, 51L)
truncate = TRUE
bandwidth=c(10,10)
n <- nrow(x)
M <- gridsize
h <- bandwidth
tau <- 3.4
if (length(h) == 1L)
h <- c(h, h)
range.x <- list(0, 0)
for (id in (1L:2L)) range.x[[id]] <- c(min(x[, id]) -
1.5 * h[id], max(x[, id]) + 1.5 * h[id])
a <- c(range.x[[1L]][1L], range.x[[2L]][1L])
b <- c(range.x[[1L]][2L], range.x[[2L]][2L])
gpoints1 <- seq(a[1L], b[1L], length = M[1L])
gpoints2 <- seq(a[2L], b[2L], length = M[2L])
gcounts <- linbin2D(x, gpoints1, gpoints2)
L <- numeric(2L)
kapid <- list(0, 0)
for (id in 1L:2L) {
L[id] <- min(floor(tau * h[id] * (M[id] - 1)/(b[id] -
a[id])), M[id] - 1L)
lvecid <- 0:L[id]
facid <- (b[id] - a[id])/(h[id] * (M[id] - 1L))
z <- matrix(dnorm(lvecid * facid)/h[id])
tot <- sum(c(z, rev(z[-1L]))) * facid * h[id]
kapid[[id]] <- z/tot
}
kapp <- kapid[[1L]] %*% (t(kapid[[2L]]))/n
if (min(L) == 0)
warning("Binning grid too coarse for current (small) bandwidth: consider increasing 'gridsize'")
P <- 2^(ceiling(log(M + L)/log(2)))
L1 <- L[1L]
L2 <- L[2L]
M1 <- M[1L]
M2 <- M[2L]
P1 <- P[1L]
P2 <- P[2L]
rp <- matrix(0, P1, P2)
rp[1L:(L1 + 1), 1L:(L2 + 1)] <- kapp
if (L1)
rp[(P1 - L1 + 1):P1, 1L:(L2 + 1)] <- kapp[(L1 + 1):2,
1L:(L2 + 1)]
if (L2)
rp[, (P2 - L2 + 1):P2] <- rp[, (L2 + 1):2]
sp <- matrix(0, P1, P2)
sp[1L:M1, 1L:M2] <- gcounts
rp2 <- fft(rp)
sp2 <- fft(sp)
rp3 <- Re(fft(rp2 * sp2, inverse = TRUE)/(P1 * P2))[1L:M1, 1L:M2]
rp4 <- rp3 * matrix(as.numeric(rp3 > 0), nrow(rp3), ncol(rp3))
list(x1 = gpoints1, x2 = gpoints2, fhat = rp4)