% 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

\name{colorbar.plot}
\alias{colorbar.plot}
%- Also NEED an '\alias' for EACH other topic documented here.
\title{ Adds color scale strips to an existing plot.}
\description{
Adds one or more color scales in a horizontal orientation, 
vertical orientation to an existing plot.
}
\usage{

colorbar.plot(x, y, strip, strip.width = 0.1, strip.length = 4 * strip.width, 
zrange = NULL, adj.x = 0.5, adj.y = 0.5, col = tim.colors(256), 
horizontal = TRUE, ...)


}
\arguments{
  \item{x}{x position of strip  in user coordinates }
  \item{y}{y position of strip in user coordinates}
  \item{strip}{ Either a vector or matrix giving the values of the color 
strip(s). If a matrix then strips are assumed to be the columns.   }
  \item{strip.width}{ Width of strip as a fraction of the plotting 
region. }
  \item{strip.length}{ Length of strip as a function of the plotting 
region. Default is a pleasing 8 times width.   }
  \item{zrange}{If a vector these are the common limits used for 
   assigning the color scale. Default is to use the range of values in 
strip. If a two column matrix, rows are used as the limits for each 
strip.}
  \item{adj.x}{ Location of strip relative to x coordinate. Most 
common values are .5 (centered), 0 (right end at x) and  1 (left end of 
at x). These are the same conventions that are used for \code{adj} in 
positioning text.}
  \item{adj.y}{Location of strip relative to y coordinate. 
Same rules as \code{adj.x} 
}
  \item{col}{ Color table used for strip. Default is our favorite 
tim.colors being a scale from a dark blue to dark red.}
  \item{horizontal}{ If TRUE draws strips horizontally. If FALSE strips 
are drawn vertically }
  \item{\dots}{ optional graphical arguments that are passed to 
the \code{image} function. }
}
\details{
This function draws the strips as a sequence of image plots added to the 
existing plot. The main work is in creating a grid ( x,y) for the image 
that makes sense when superimposed on the plot. 
Note that although the columns of strip are considered as 
separate strips these can be oriented either horizontally or vertically 
based on the value of \code{horizontal}. The rows of zrange are
essentially the \code{zlim} argument passed to the \code{image} function 
when each strip is drawn. 

Don't forget to use \code{locator} to interactively determine positions. 
\code{text} can be used to label points neatly in conjunction with 
setting adj.x and adj.y.  Although this function is inefficient for 
placing images at arbitrary locations on a plot the code can be easily 
adapted to do this. 

This function was created to depict univariate posterior 
distribution on a map. The values are quantiles of the distribution and 
the strips when added under a common color scale give an overall 
impression of location and scale for several distributions. 
 }
\author{Doug Nychka}

\seealso{ image.plot, arrow.plot, add.image}

\examples{
# set up a plot but don't plot points  and no "box"
plot( 1:10, (1:10)*10, type="n", bty="n") 
# of course this could be anything 

y<- cbind( 1:15, (1:15)+25)

colorbar.plot( 2.5, 30, y)
points( 2.5,30, pch="+", cex=2, adj=.5)
# note that strip is still in 1:8 aspect even though plot has very 
# different ranges for x and y. 

# adding legend using image.plot
zr<- range( c( y))
image.plot( legend.only=TRUE, zlim= zr) 
# see help(image.plot) to create more room in margin etc. 

zr<- rbind( c(1,20), c(1,100)) # separate ranges for columns of y. 
colorbar.plot( 5, 70, y, adj.x=0, zrange= zr)
# some reference lines to show placement
xline( 5, lty=2) # strip starts at x=5 
yline(70, lty=2)  # strip is centered around y=7 (because adj.y=.5 by default)

# many strips on common scale.

y<- matrix( 1:200, ncol=10)
colorbar.plot( 2, 75, y, horizontal=FALSE, col=rainbow(256)) 

# Xmas strip
y<- cbind( rep( c(1,2),10))
y[15] <- NA # NA's should work 
colorbar.plot( 6, 45, y, adj.y=1,col=c("red", "green"))
text(6,48,"Christmas strip", cex=2)

# lennon thumbnail
# there are better ways to this ... see add.image for example.
data( lennon)
colorbar.plot( 7.5,22, lennon, 
           strip.width=.25, strip.length=.25, col=grey(seq( 0,1,,256)))

}
\keyword{ hplot }% at least one, from doc/KEYWORDS