# [R] Matrix-like plot

Martin Maechler maechler at stat.math.ethz.ch
Fri May 31 17:05:13 CEST 2002

```>>>>> "GS" == Gavin Simpson <gavin.simpson at ucl.ac.uk> writes:

< ... >

GS> What I do not know who to do is to plot the matrix-like plot.  I want to
GS> have a point for every value greater than zero in the matrix.  So that
GS> if in sample/row 1, species 1 and 2 were present at 25% and 75%
GS> respectively but species 3 was absent, I would want 2 points, one for
GS> each species present scaled relative to their abundance.  I presume what
GS> I would actually do is plot an expand.grid() object and vary the cex by
GS> the values in the matrix so that zero values had zero cex, but I am not
GS> sure how to go about doing this.

I'd look at
sunflowerplot()
symbols()
and stars()

GS> An alternative could be to use image()
GS> to plot coloured boxes for each cell based on the abundances.  I tried
GS> this initially like so:

>> test <- expand.grid(x=1:47, y=1:83)
>> names(test)
GS>  "x" "y"
GS> abundances
GS> Error in image.default(test, z = cladocera) :
GS> increasing x and y values expected

GS> I am now stuck as to how generate the x and y points for image.

I don't have `cladocera' but the following works

> image(list(x = u, y = v), z=z)
> str(z <- outer(u,v, function(x,y){x <- x-6; sin(x)*exp(-(x/4^2 + (y-20)/3^2))}))
num [1:10, 1:20]  3.563  2.642 -0.463 -2.801 -2.435 ...
> image(list(x = u, y = v), z=z)

Martin Maechler <maechler at stat.math.ethz.ch>	http://stat.ethz.ch/~maechler/
Seminar fuer Statistik, ETH-Zentrum  LEO C16	Leonhardstr. 27
ETH (Federal Inst. Technology)	8092 Zurich	SWITZERLAND
phone: x-41-1-632-3408		fax: ...-1228			<><
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```