labdsv (version 2.0-1)

plot.thull: Plotting a Tensioned Hull

Description

A tensioned hull is a minimum volume container for specified elements of an ordination. A ‘thull’ object is returned as an invisible object by plotting a thull of an NMDS or PCO (or MFSO). Subsequently plotting the returned thull results in an ‘image’ of the representation.

Usage

# S3 method for thull
plot(x,col=rainbow(20),levels=NULL,cont=TRUE,
          xlab=x$xlab,ylab=x$ylab,main=x$main,...)

Value

Produces a plot on the current graphic device.

Arguments

x

an object of class ‘thull’ from function thull

col

the color to use plotting the contours

levels

the specific levels desired for the contours

cont

a logical variable to control plotting contours on the image representation of the tensioned hull

xlab

the X axis label

ylab

the Y axis label

main

the main title

...

other graphics parameters

Author

David W. Roberts http://ecology.msu.montana.edu/droberts/droberts.html

Details

Tensioned hull analysis fits a minimum volume envelope to specific points in an ordination. A tensioned hull object is returned from function thull of a ordination of class ‘dsvord’. This function plots the resulting tensioned hull as an image, with optional overlays of contours.

Examples

data(bryceveg) # returns a data.frame called bryceveg
dis.bc <- dsvdis(bryceveg,'bray') # calculates a Bray-Curtis 
                                  # dissimilarity matrix
nmds.bc <- nmds(dis.bc) # calculates an NMDS ordination
plot(nmds.bc) # plots the ordination on the current device
demo.thull <- thull(nmds.bc,bryceveg$arcpat,0.25) # calculates 
                        # the tensioned hull representing the 
                        # distributtion of a species
plot(demo.thull) # portrays the image version of the tensioned hull