[R] Negative value on ternaryplot

[Christos Hatzis]

Ternary plots are typically used to plot triplets of values (e.g.
composition of 3 components) that add up to 100% or 1. In this context, I am
not sure what a negative value means.  Do the 3 numbers in your application
still add up to 100%?  Alternatively, would it be meaningful to translate
the data along the dimension with negative values to shift them to the
positive quadrant?

-Christos

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Greg Snow
Sent: Thursday, May 18, 2006 2:37 PM
To: Poizot Emmanuel; r-help at stat.math.ethz.ch
Subject: Re: [R] Negative value on ternaryplot

There are also the functions: triangle.plot in package ade4, triplot in
package TeachingDemos, tri in package cwhtool, and soil.texture in package
plotrix.  Perhaps one of these other functions will work better for you (all
do the triangular plots, each with different bells and whistles).

triplot from TeachingDemos has an option to add to an existing plot (the
idea being that you already created one triplot and are now adding more
points/lines to it).  You could set up your own plot and axes then use
triplot with add=TRUE to plot your points.

If none of those work for you then you could look at the source code of
any of them to see what modifications would help.   

Hope this helps,

--
Gregory (Greg) L. Snow Ph.D.
Statistical Data Center
Intermountain Healthcare
greg.snow at intermountainmail.org
(801) 408-8111
 

-----Original Message-----
From: r-help-bounces at stat.math.ethz.ch
[mailto:r-help-bounces at stat.math.ethz.ch] On Behalf Of Poizot Emmanuel
Sent: Thursday, May 18, 2006 7:05 AM
To: r-help at stat.math.ethz.ch
Subject: [R] Negative value on ternaryplot

Dear all,
I found a wonderful package (vcd) able to plot ternary diagrams, i.e. 
ternaryplot (thanks D. Meyer).
The problem is that one of three variable has negative values.
If I use the ternaryplot function but some points are outside the
triangle, as value en negative.
Is it possible to make the ternary diagram fit exactly the cloud points
?
Regards

------------------------------------------------
Emmanuel Poizot
Cnam/Intechmer
B.P. 324
50103 Cherbourg Cedex

Phone (Direct) : (00 33)(0)233887342
Fax : (00 33)(0)233887339

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