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#
# fields is a package for analysis of spatial data written for
# the R software environment.
# Copyright (C) 2022 Colorado School of Mines
# 1500 Illinois St., Golden, CO 80401
# Contact: Douglas Nychka, douglasnychka@gmail.edu,
#
# 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
##END HEADER
"image.plot" <- function(..., add = FALSE,
breaks= NULL, nlevel = 64, col = NULL,
horizontal = FALSE, legend.shrink = 0.9, legend.width = 1.2,
legend.mar = ifelse(horizontal, 3.1, 5.1), legend.lab = NULL,
legend.line= 2,
graphics.reset = FALSE, bigplot = NULL, smallplot = NULL,
legend.only = FALSE, lab.breaks = NULL,
axis.args = NULL, legend.args = NULL, legend.cex=1.0, midpoint = FALSE, border = NA,
lwd = 1, verbose=FALSE) {
# Thanks to S. Koehler and S. Woodhead
# for comments on making this a better function
#
# save current graphics settings
old.par <- par(no.readonly = TRUE)
# set defaults for color scale
# note this works differently than the image function.
if( is.null(col)) {
col<- tim.colors(nlevel)}
else{
nlevel<- length( col)
}
# figure out zlim from passed arguments
# also set the breaks for colors if they have not been passed,
info <- imagePlotInfo(..., breaks=breaks, nlevel=nlevel)
# breaks have been computed if not passed in the call
breaks<- info$breaks
if( verbose){
print(info)
}
if (add) {
big.plot <- old.par$plt
}
if (legend.only) {
graphics.reset <- TRUE
}
if (is.null(legend.mar)) {
legend.mar <- ifelse(horizontal, 3.1, 5.1)
}
# figure out how to divide up the plotting real estate
temp <- imageplot.setup(add = add, legend.shrink = legend.shrink,
legend.width = legend.width, legend.mar = legend.mar,
horizontal = horizontal, bigplot = bigplot, smallplot = smallplot)
# bigplot has plotting region coordinates for image
# smallplot has plotting coordinates for legend strip
smallplot <- temp$smallplot
bigplot <- temp$bigplot
# draw the image in bigplot, just call the R base function
# or poly.image for polygonal cells
# note the logical switch
# for poly.grid is parsed out of call from image.plot.info
if (!legend.only) {
if (!add) {
par(plt = bigplot)
}
if (!info$poly.grid) {
image(..., breaks=breaks, add = add, col = col)
}
else {
poly.image(..., add = add,breaks=breaks, col = col,
midpoint = midpoint,
border = border, lwd.poly = lwd)
}
big.par <- par(no.readonly = TRUE)
}
##
## check dimensions of smallplot
if ((smallplot[2] < smallplot[1]) | (smallplot[4] < smallplot[3])) {
par(old.par)
stop("plot region too small to add legend\n")
}
# Following code draws the legend using the image function
# and a one column image.
# What might be confusing is the values of the "image" are the same
# as the locations on the legend axis.
# Moreover the image values are in the middle of each breakpoint category
# thanks to Tobias Nanu Frechen and Matthew Flickinger
# for sorting out some problems with the breaks position in the legend.
ix <- 1:2
iy<- breaks
nBreaks<- length( breaks)
midpoints<- (breaks[1:(nBreaks-1)] + breaks[2:nBreaks] )/2
iz <- matrix(midpoints, nrow = 1, ncol = length(midpoints))
if( verbose){print(breaks)
print( midpoints)
print( ix)
print( iy)
print( iz)
print( col)}
#
# next par call sets up a new plotting region just for the legend strip
# at the smallplot coordinates
par(new = TRUE, pty = "m", plt = smallplot, err = -1)
# draw color scales the two cases are horizontal/vertical
# add a label if this is passed.
if (!horizontal) {
image(ix, iy, iz, xaxt = "n", yaxt = "n", xlab = "",
ylab = "", col = col, breaks=breaks)
}
else {
image(iy, ix, t(iz), xaxt = "n", yaxt = "n", xlab = "",
ylab = "", col = col, breaks=breaks)
}
# create the argument list to draw the axis
# this avoids 4 separate calls to axis and allows passing extra
# arguments.
if (!is.null(lab.breaks)) {
# axis with labels at break points
axis.args <- c(list(side = ifelse(horizontal, 1, 4),
mgp = c(3, 1, 0), las = ifelse(horizontal, 0, 2),
at = breaks, labels = lab.breaks), axis.args)
}
else {
# If lab.breaks is not specified ( with or without breaks), pretty
# tick mark locations and labels are computed internally,
# or as specified in axis.args at the function call
axis.args <- c(list(side = ifelse(horizontal, 1, 4),
mgp = c(3, 1, 0), las = ifelse(horizontal, 0, 2)),
axis.args)
}
#
# now add the axis to the legend strip.
# notice how all the information is in the list axis.args
do.call("axis", axis.args)
# add a box around legend strip
# box()
#
# add a label to the axis if information has been supplied
# using the mtext function. The arguments to mtext are
# passed as a list like the drill for axis (see above)
#
if (!is.null(legend.lab)) {
legend.args <- list(text = legend.lab, side = ifelse(horizontal,
1, 4), line = legend.line, cex=legend.cex)
# just guessing at a good default for line argument!
}
# add the label using mtext function
if (!is.null(legend.args)) {
do.call(mtext, legend.args)
}
#
# clean up graphics device settings
# reset to larger plot region with right user coordinates.
mfg.save <- par()$mfg
if (graphics.reset | add) {
par(old.par)
par(mfg = mfg.save, new = FALSE)
invisible()
}
else {
par(big.par)
par(plt = big.par$plt, xpd = FALSE)
par(mfg = mfg.save, new = FALSE)
# Suggestion from Karline Soetaert <Karline.Soetaert@nioz.nl>
# this is to reset margins to be based on the mar arguments
# par(mar = par("mar")) or
# par(mar = big.par$mar)
# unfortunately this causes problems by allowing plotting outside of the
# original plot region.
invisible()
}
}
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