Kcross:

# dev pcf-cross inhomog faster. Box correction, just for 2 points, faster
# than pcf in spatstat when only few ranges to compute.

# library(spatstat)
# library(Rcpp)
#
# sourceCpp("ipcf_cross_all_box.cpp")


# quick cross pcf, border correction
# assumes rectangnular window
ipcf_cross_all_box <- function(x, r, int, adjust = 1, correction = TRUE) {
  xy <- as.matrix(coords(x))
  types <-  as.integer(marks(x))
  ntypes <- length(unique(types))
  bb <- as.matrix( with(x$window, cbind(xrange, yrange)) )
  # check int
  m <- "intensities needed. Vector, int per point"
  if(missing(int)) stop(m)
  if(length(int) != x$n) stop(m)
  # go
  V <- c_ipcf_cross_2d_box(xy, bb, ntypes, types, int, r, adjust, correction)
  #
  # scaling
  vol <- area(x$window)
  Ss <- sapply(split(int, types), function(x) vol/sum(1/x))
  S <- matrix(Ss, ntypes, ntypes)
  # compile the pcf's
  G <- array(dim = c(ntypes, ntypes, length(r)))
  for(i in 1:length(r)){
    G[,,i] <- matrix(V[[i]], ncol = ntypes, nrow = ntypes) * S
  }

  # done
  G
}

####################################################
# quick univ inhom pcf, translate border correction
# assumes rectangnular window
ipcf_box <- function(x, r, int, adjust = 1, correction = TRUE){
  m <- "int should be a vector, one value per point."
  if(missing(int)) stop(m)
  if(x$n != length(int)) stop(m)
  xy <- as.matrix(coords(x))
  bb <- as.matrix( with(x$window, cbind(xrange, yrange)) )
  bw <- 0.15 * adjust / sqrt(mean(int))
  #
  S <- area(x$window)/sum(1/int)
  # go
  V <- c_ipcf_2d_box(xy, bb, int, bw, r, adjust, correction)
  #
  S*V
}


####################################################
# TEST
# univariate ig

if(0){
  library(spatstat)
  set.seed(12)
  x <- rMatClust(100,.05, 10)
  r <- seq(0, .3, l = 50)
  int <- density(x)[x]
  t0 <- system.time( g <- pcfinhom(x, r=r, lambda = int,
                                   divisor ="d", correction ="trans") )
  t1 <- system.time( gg <- ipcf_box(x, r = r, int = int) )
  par(mfrow=c(1,1))
  plot(r, g$trans, "l", lwd=3)
  lines(r, gg, col=3, lty=2)
  abline(h = 1, col=2)
  print(rbind(t0,t1))
  # close enough
}



# multiv
if(0){
  library(spatstat)
  set.seed(12)
  n <- 700
  m <- 10
  x <- setmarks( rpoint(n), factor( sample(1:m, n, replace=T) )  )
  r <- seq(0, .4, l = 50)

  int <- (den<-density(x, adjust = 2)/m)[x]

  t0 <- system.time( g <- pcfcross.inhom(x, r=r, i=1, j=2, adjust=2,
                                         lambdaI = den, lambdaJ=den,
                                   divisor ="d", correction ="trans") )

  t1 <- system.time( gg <- ipcf_cross_all_box(x, r = r, int = int) )
  par(mfrow=c(1,1))
  plot(r, g$trans, "l", lwd=3, ylim= c(0,2))
  lines(r, gg[1,2,]/2, col=3, lty=2)
  abline(h = 1, col=2)
  print(rbind(t0,t1))
  # close enough
}