# fields, Tools for spatial data
# Copyright 2004-2011, Institute for Mathematics Applied Geosciences
# University Corporation for Atmospheric Research
# Licensed under the GPL -- www.gpl.org/licenses/gpl.html
"as.surface" <- function(obj, z, order.variables = "xy") {
    #
    if (is.list(obj)) {
        grid.list <- obj
    }
    if (is.matrix(obj)) {
        grid.list <- attr(obj, "grid.list")
    }
    #
    #  OK now have a grid, parse this to figure
    #  nx and ny the x and y sequences and extract names
    #
    hold <- parse.grid.list(grid.list, order.variables = "xy")
    #
    # note that coercing z to a matrix is just reformatting
    # using the standard ordering.
    #
    # output list is all the grid stuff and the matrix z.
    c(hold, list(z = matrix(z, ncol = hold$ny, nrow = hold$nx)))
}