imagebar {bigsplines}

Displays a Color Image with Colorbar

Description

This is a modification to the R function image that adds a colorbar to the margin.

Usage

imagebar(x,y,z,xlim=NULL,ylim=NULL,zlim=NULL,
         zlab=NULL,zcex.axis=NULL,zcex.lab=NULL,
         zaxis.at=NULL,zaxis.labels=TRUE,
         col=NULL,ncolor=21,drawbar=TRUE,zline=2,
         pltimage=c(.2,.8,.2,.8),pltbar=c(.82,.85,.2,.8),...)

Arguments

x, y

Locations of grid lines at which the values in z are measured. These must be finite, non-missing and in (strictly) ascending order. If only x is given, the input x is treated as z.

z

A matrix containing the values to be plotted (NAs are allowed). If x and y are missing, a sequence from 0 to 1 is used for plotting.

xlim, ylim

Ranges for the plotted x and y values, defaulting to the ranges of x and y.

zlim

The minimum and maximum z values for which colors should be plotted, defaulting to the range of the finite values of z.

zlab

Label for the colorbar.

zcex.axis

The magnification to be used for the z-axis annotation (colorbar scale).

zcex.lab

The magnification to be used for the z-axis label (zlab).

zaxis.at

The points at which tick-marks are to be drawn for the colorbar. Points outside of the range of zlim will not be plotted.

zaxis.labels

This can either be a logical value specifying whether (numerical) annotations are to be made at the tickmarks, or a character or expression vector of labels to be placed at the tickpoints.

col

Color scheme to use. Default is from blueviolet (low) to red (high).

ncolor

The number of colors to use in the color scheme.

drawbar

Logical indicating if the colorbar should be drawn.

zline

Number of lines into the margin at which the axis line will be drawn (see axis).

pltimage

A vector of the form c(x1, x2, y1, y2) giving the coordinates of the image region as fractions of the current figure region (see par).

pltbar

A vector of the form c(x1, x2, y1, y2) giving the coordinates of the colorbar region as fractions of the current figure region (see par).

...

Additional arguments to be passed to image (e.g., xlab, ylab, main, cex, cex.axis, cex.lab, etc.)

Value

Produces an image plot with a colorbar.

Author(s)

Nathaniel E. Helwig <[e-mail]>

Examples

##########   EXAMPLE 1   ##########

myfun <- function(x){
  2*sin(sqrt(x[,1]^2+x[,2]^2+.1))/sqrt(x[,1]^2+x[,2]^2+.1)
}
x <- expand.grid(seq(-8,8,l=100),seq(-8,8,l=100))
imagebar(seq(-8,8,l=100),seq(-8,8,l=100),matrix(myfun(x),100,100),
         xlab=expression(italic(x)[1]),ylab=expression(italic(x)[2]),
         zlab=expression(hat(italic(y))),zlim=c(-0.5,2),zaxis.at=seq(-0.5,2,by=0.5))


##########   EXAMPLE 2   ##########

myfun <- function(x1v,x2v){
  sin(2*pi*x1v) + 2*sin(sqrt(x2v^2+.1))/sqrt(x2v^2+.1)
}
x <- expand.grid(x1v=seq(0,1,l=100),x2v=seq(-8,8,l=100))
imagebar(seq(0,1,l=100),seq(-8,8,l=100),matrix(myfun(x$x1v,x$x2v),100,100),
         col=c("red","orange","yellow","white"),xlab="x1v",ylab="x2v",
         zlab=expression(hat(italic(y))),zlim=c(-1.5,3),zaxis.at=seq(-1.5,3,by=0.5))


##########   EXAMPLE 3   ##########

myfun <- function(x1v,x2v){
  sin(3*pi*x1v) + sin(2*pi*x2v) + 3*cos(pi*(x1v-x2v))
}
x <- expand.grid(x1v=seq(-1,1,l=100),x2v=seq(-1,1,l=100))
imagebar(seq(-1,1,l=100),seq(-1,1,l=100),matrix(myfun(x$x1v,x$x2v),100,100),
         col=c("blue","green","light green","yellow"),xlab="x1v",ylab="x2v",
         zlab=expression(hat(italic(y))),zlim=c(-5,5),zaxis.at=c(-5,0,5),
         zaxis.labels=c("low","med","high"))