https://github.com/cran/spatstat
Tip revision: 908b22c6a5d1f38ed00b44c11d7a7166eeeecaa3 authored by Adrian Baddeley on 10 August 2010, 14:17:18 UTC
version 1.20-2
version 1.20-2
Tip revision: 908b22c
levelset.R
# levelset.R
#
# $Revision: 1.3 $ $Date: 2008/07/16 17:39:32 $
#
# level set of an image
levelset <- function(X, thresh, compare="<=") {
# force X and thresh to be evaluated in this frame
verifyclass(X, "im")
thresh <- thresh
switch(compare,
"<" = { A <- eval.im(X < thresh) },
">" = { A <- eval.im(X > thresh) },
"<=" = { A <- eval.im(X <= thresh) },
">=" = { A <- eval.im(X >= thresh) },
"==" = { A <- eval.im(X == thresh) },
"!=" = { A <- eval.im(X != thresh) },
stop(paste("unrecognised comparison operator", sQuote(compare))))
W <- as.owin(eval.im(ifelse(A, 1, NA)))
return(W)
}
# compute owin containing all pixels where image expression is TRUE
solutionset <- function(..., envir) {
if(missing(envir))
envir <- parent.frame()
A <- eval.im(..., envir=envir)
if(A$type != "logical")
stop("Evaluating the expression did not yield a logical-valued image")
W <- as.owin(eval.im(ifelse(A, 1, NA)))
return(W)
}