Colin,
If your propose is to create a ternary plot with points and vectors, I think
easier do this with graphics based plots instead of trellis based plots.
Although, with little work you can do with trellis too. I gave you a
reproducible code to put an arrow in a ternary plot. I use the function
locator() to extract coordinates. The code is the following
#------------------------------------------------------------------------------------------
# package and related documentaion
require(plotrix)
help.search("triax")
help(triax.plot, html=TRUE)
#------------------------------------------------------------------------------------------
# toy data
data(soils)
str(soils)
#------------------------------------------------------------------------------------------
# creating a ternary plot
triax.plot(soils[1:10,], main="DEFAULT")
#------------------------------------------------------------------------------------------
# extracting coodinates by mouse click on the plot (cartesian coordinates, x
and y axis)
id <- locator(n=2) # click on the plot to extract 2 coodinates
#------------------------------------------------------------------------------------------
# draw an arrow with the coordinates extracted
arrows(id$x[1], id$y[1], id$x[2], id$y[2])
#------------------------------------------------------------------------------------------
At your disposal.
Walmes.
============================================================
Walmes Marques Zeviani
LEG (Laboratório de Estatística e Geoinformação)
Departamento de Estatística - Universidade Federal do Paraná
fone: (+55) 41 3361 3573
VoIP: (3361 3600) 1053 1173
e-mail: wal...@ufpr.br / @walmeszeviani
homepage: http://www.leg.ufpr.br/~walmes
============================================================
> Date: Mon, 14 Feb 2011 20:05:54 +0000
> From: colin.bl...@bristol.ac.uk
> To: walmeszevi...@hotmail.com
> Subject: ternary contour plot
>
> Dear Walmes,
>
> Firstly, thank you for distributing your ternary contour plot code.
>
> could I ask you a question about it, hopefully you will be able to
> answer it quite simply and so save me some time trying to work out what
> it is that the function is actually doing.
>
> Essentially I wish to overlay points and vectors onto the ternary
> contour plot. Now can I do this by:
>
> a): extracting the adjusted x y coordinates and using it with triax.fill
>
> or
>
> b) can I plot my vectors (arrows) and points onto the grid that is
> created by levelplot.ternary
>
> if either or both are true do you know how I would go about a)
> extracting or b) inputing the relevent data?
>
> I would be grateful for your advice,
>
> best regards,
>
> colin
>
> --
> **********************************************************************************
> **********************************************************************************
>
> Dr Colin Bleay
> Station d'Ecologie Experimentale du CNRS,
> 09200 Moulis,
> France.
>
> Tel: +33 5 61 04 03 61
> Fax: +33 5 61 96 08 51
> email: colin.bl...@ecoex-moulis.cnrs.fr
> Webpage: http://www.ecoex-moulis.cnrs.fr/Staffpages/ColinBleay.htm
>
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