R/ASTIKhat.R

In stpp: Space-Time Point Pattern Simulation, Visualisation and Analysis

ASTIKhat <- function(xyt,s.region,t.region,lambda,dist,times,ang=2*pi,correction="border"){

  verifyclass(xyt,"stpp")
  
  correc=c("none","border","modified.border","translate")
  id <- match(correction, correc, nomatch = NA)
  if (any(nbg <- is.na(id))) {
    mess <- paste("unrecognised correction method:", paste(dQuote(correction[nbg]), collapse = ","))
    stop(mess, call. = FALSE)
  }
  id = unique(id)	
  correc2 = rep(0,4)
  correc2[id] = 1	
  
  dup <- any(duplicated(data.frame(xyt[,1], xyt[,2], xyt[,3])))
  if (dup == TRUE){
    messnbd <- paste("Space-time data contains duplicated points")
    warning(messnbd,call. = FALSE)
  }
  
  if (missing(s.region)) s.region <- sbox(xyt[,1:2], xfrac=0.01, yfrac=0.01)
  if (missing(t.region)){
    xr = range(xyt[,3], na.rm = TRUE)
    xw = diff(xr)
    t.region <- c(xr[1]- 0.01 * xw, xr[2] + 0.01 * xw)
  }    
  bsupt <- max(t.region)
  binft <- min(t.region)
  
  xp <- s.region[,1]
  yp <- s.region[,2]
  nedges <- length(xp)
  yp <- yp - min(yp) 
  nxt <- c(2:nedges, 1)
  dx <- xp[nxt] - xp
  ym <- (yp + yp[nxt])/2
  Areaxy <- -sum(dx * ym)
  
  if (Areaxy > 0){
    bdry <- owin(poly = list(x = s.region[,1], y = s.region[,2]))
  }else{
    bdry <- owin(poly = list(x = s.region[,1][length(s.region[,1]):1], y = s.region[,2][length(s.region[,1]):1]))
  }
  
  if (missing(dist)){
    rect = as.rectangle(bdry)
    maxd = min(diff(rect$xrange), diff(rect$yrange))/4
    dist = make.even.breaks(maxd, npos=15)$r
  } 
  
  if (missing(times))  {
    maxt = (bsupt-binft)/4
    times = make.even.breaks(maxt, npos=15)$r
  }
  
  dist <- sort(dist)
  if(dist[1] == 0) dist = dist[-1]
  times <- sort(times)
  if(times[1] == 0) times = times[-1]
  
  ok <- inside.owin(xyt[,1],xyt[,2],w=bdry)
  xyt.ins <- data.frame(x=xyt[,1][ok],y=xyt[,2][ok],t=xyt[,3][ok])
  xyt.in <- .intim(xyt.ins,t.region)

  pts <- xyt.in[,1:2]
  xytimes <- xyt.in[,3]
  ptsx <- pts[, 1]
  ptsy <- pts[, 2]
  ptst <- xytimes
  npt <- length(ptsx)
  ndist <- length(dist)
  ntimes <- length(times)
  area <- area(bdry) * (bsupt - binft)
  astkf <- array(0,dim=c(ndist, ntimes, 4))
  
  if(missing(lambda)){
    misl <- 1
    lambda <- rep(npt/area, npt)
  }
  else misl <- 0
  if (length(lambda) == 1) lambda <- rep(lambda, npt)
  
  storage.mode(astkf) <- "double"
  
  wbi = array(0, dim = c(npt, ndist, ntimes))
  wbimod = array(0, dim = c(npt, ndist, ntimes))
  wt = array(0, dim = c(npt, npt)) 
  
  options(warn = -1)
  
  pppxy = ppp(x = ptsx, y = ptsy, window = bdry)
  
  #  correction=="border" and "modified border"
  if(any(correction=="border")|any(correction=="modified.border")){
    
    bi=bdist.points(pppxy)
    bj=.bdist.times(xytimes,t.region)
    
    for(i in 1:ndist){ 
      for(j in 1:ntimes){
        wbi[,i,j] = (bi>dist[i])*(bj>times[j])/sum((bi>dist[i])*(bj>times[j])/lambda)
        wbimod[,i,j] = (bi>dist[i])*(bj>times[j])/(eroded.areas(bdry,dist[i])*.eroded.areat(t.region,times[j]))
      } }
    wbi[is.na(wbi)] <- 0
    wbimod[is.na(wbimod)] <- 0
  }
  
  # correction=="translate"
  if(any(correction=="translate"))
  {
    wtt = .overlap.tint(xytimes,t.region)
    wts = edge.Trans(pppxy)
    wt = wtt*wts
    wt=1/wt
  }
  
  options(warn = 0)	
  
  astk <- .Fortran("astk", as.double(ptsx),
                   as.double(ptsy), as.double(ptst),
                   as.integer(npt), as.double(lambda),
                   as.double(ang), as.double(dist),
                   as.integer(ndist), as.double(times),
                   as.integer(ntimes), as.double(wbi),
                   as.double(wbimod), as.double(wt),
                   as.integer(correc2), (astkf))
  
  astkf <- astk[[15]]
  
  astkf[,,c(1,2,4)]=astkf[,,c(1,2,4)]/area
  
  if(length(id)==1) AKhat=as.array(astkf[,,id])
  else{
    AKhat=list()
    for(i in 1:length(id)) AKhat[[i]]=astkf[,,id[i]]	
    names(AKhat)=correc[id]
  }
  correction=correc[id]
  
  
invisible(return(list(AKhat=AKhat,dist=dist,times=times,correction=correction)))
}