Mike Livermore – CSI 773 – Week 2 Assignment – Functions and bar plots - September 2010

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coloredMatrix = function(mat,nbreaks=5,colors,

                title="",padx=.5,pady=.5,border=NULL){

                # create a matrix of integer with values from 1 to nbreaks

                # This use nbreaks equally space intevals over the range of the data 

                matColorSubs = cut(mat,breaks=nbreaks,include.lowest=T)

                # Define colors if not supplied in the function argument

                #     The ones below are diverging colors from ColorBrewer

                if(missing(colors)){

                                  colors=c("#2C7BB6","#ABD9E9","#FFFFBF","#FDAE61","#CA373B")

                }

                # We generate x and y coordinates for the centers of the rectangles

                # Start with coordinates yloc and xloc of a single row and a single column 

                nr = nrow(mat)

                nc = ncol(mat)

                yloc = nr:1     # Most people think of the top row as row 1

                xloc = 1:nc

                #  Produce all pairing of one element for each of the two vectors

                xyLat = expand.grid(list(y=yloc,x=xloc))

                # Extract the vectors in the list as separate vectors

                y=xyLat$y

                x=xyLat$x

                # Set of the plot scale

                plot(c(1-padx,padx+nc),c(1-pady,pady+nr),type="n",axes=F,

                                                xlab="",ylab="",main=title,cex=1.2)

                # Set the size of the rectangles relative to the grid and plot.

                # The rectangle centers at integer values

                # rect needs the lower left x and y and the upper right x and y

                # For x-dx and y-dy  to x+dx and y+dy what should dx and dy

                # be for the rectangles to touch?  

dx = .5  # This is a single value that will replicate when used below

                dy = .5  # This is a single value that will replicate when used below

                rect(x-dx,y-dy,x+dx,y+dy,border=border,col=colors[matColorSubs])

                return("Done")

}

## End

windows()

mat = matrix(rnorm(2500),ncol=50)

coloredMatrix(mat,border="gray")

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