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question for the R community : Plot RDA biplot without axis ?

7 messages · Sarah Loboda, Gavin Simpson, Pierre THIRIET +2 more

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On Mon, 2013-02-25 at 13:18 -0500, Sarah Loboda wrote:
A problem is the call to text() ( which calls text.cca() ). It doesn't
pass on arguments to the underlying axis() calls and hence you can't do
what you are trying to do with that function directly.

Not sure why you want the axis to be white - that draws an axis so it
will obscure anything drawn before it with white paint.

The only solution at the moment will be to modify the vegan:::text.cca()
function to change the two calls to axis() at the end of the function
definition. I suspect you could just copy the body of vegan:::text.cca
and put it into your own function, but I haven't tried it. If that fails
due to namespace issues, then use assignInNamespace() to assign your
function to the text.cca function in vegans namespace.

See the relevant help pages on how to do this. I'm about to leave the
office so I can't help further now, but if you have trouble email back
to the list and I'll see about cooking up and example...

All the best

Gavin
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Dear List,

I am unsure if this is the right forum to direct my question and if it is not i apologise. 

My query is more of the theoretical / "can it be done" type than practical.


I have modelled time series of fish catch in relation to a suite of environmental variables (SST, ChlA etc) using a dynamic factor analysis. 

The output from this is usual model output including a AIC value for each model. I then calculated AIC difference and chucked away candidate models with a AIC difference score of < 2 i.e. as per Burnham and Anderson.

I then calculated the relative variable importance from the Akaike weights.

I did this for 52 distinct sites.

So I have for site 1

Chla = 1 - implying very important
SST = 0.0 - - implying not very important
Depth = 0.3

site 2

Chla = 0.4
SST = 0.2
Depth = 0.3

Etc etc

Now my question - In my eyes it is reasonable to cluster these scores using vegan for example in order to understand which sites share similarities in relation to what is important in explain variance in fish catch. I have done it, it works, and the results are nice and make sense but is there something i am missing - i have not been able to find other studies using this approach?

Thanks

Chris


Chris Mcowen
Postdoctoral Scientist, Nippon Foundation Nereus Senior Fellow
Marine Assessment and Decision Support Programme

UNEP World Conservation Monitoring Centre
219 Huntingdon Road
Cambridge CB3 0DL
United Kingdom
Switchboard: +44 (0)1223 277 314
Fax: +44 (0)1223 277 136

www.unep-wcmc.org
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Sarah,

We indeed insist on drawing scale of arrows for text() and point() function of cca/rda/capscale. Currently the only way to avoid this is to edit the function. I'll see what to do with this.

One piece of advice: do not use col.axis = "white" which will draw white axes. The background of the graph is transparent but the plot is displayed on white canvas so that you cannot see white axes. The white axes are still, like you will see if you look at the graph against some other colour (which happens most easily if you copy the graph and display it in slides or in a poster with coloured background). The canonical way is to suppress axes:

plot(dune.cca, type="n", scaling = 2, axes = FALSE, xlab = "", ylab = "")

Here 'axes' suppress drawing axes and to be sure, xlab and ylab use zero-length strings "" so that axis labels are also suppressed. You can later use

box()

to frame the empty graph if needed.

Cheers, Jari Oksanen
On 26 Feb 2013, at 3:49, Sarah Loboda wrote:

            
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Sarah,

I added argument 'axis.bp' to text.cca and points.cca functions. To upgraded functions can be found in http://vegan.r-forge.r-project.org/ (rev2452), and will probably be included in the next minor release of vegan (2.0-7) scheduled for March, 2013.

You can also get the single files from R-Forge, or you can install devel version of vegan with

install.packages("vegan", repos="http://r-forge.r-project.org")

It will take a day at minimum to get the version packaged in R-Forge.

Cheers, Jari Oksanen
On 26 Feb 2013, at 3:49, Sarah Loboda wrote: