# fields  is a package for analysis of spatial data written for
# the R software environment .
# Copyright (C) 2018
# University Corporation for Atmospheric Research (UCAR)
# Contact: Douglas Nychka, nychka@ucar.edu,
# National Center for Atmospheric Research, PO Box 3000, Boulder, CO 80307-3000
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with the R software environment if not, write to the Free Software
# Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA
# or see http://www.r-project.org/Licenses/GPL-2 
which.max.matrix <- function(z) {
    if (!is.matrix(z)) {
        stop("Not a matrix")
    }
    m <- nrow(z)
    n <- ncol(z)
    # take care of NAs
    ind <- which.max(z)
    iy <- trunc((ind - 1)/m) + 1
    ix <- ind - (iy - 1) * m
    return(cbind(ix, iy))
}


which.max.image <- function(obj) {
    ind.z <- which.max.matrix(obj$z)
    return(list(x = obj$x[ind.z[, 1]], y = obj$y[ind.z[, 2]], 
        z = obj$z[ind.z], ind = ind.z))
}