[R-sig-eco] vegan RDA triplot species arrows

[Tyler Smith]

Gavin Simpson <gavin.simpson at ucl.ac.uk>
writes:

> On Wed, 2011-05-04 at 15:44 -0400, Tyler Smith wrote:
>> Why does vegan not plot species as arrows in plot? I know how to use
>> scores() and arrows() to create my own arrows, but it seems odd that
>> this feature is not built in. Is there ever a situation where species
>> *should* be plotted as points rather than arrows?
>> 
> I don't know, but it might having something to do with Jari's aversion
> to using linear methods for species data ;-)

Oh, right. I guess the pre-transformation of species data is still a
recent development, so maybe it made sense to discourage using RDA with
species as dependent variables.

> More seriously, perhaps this hasn't/didn't occur to the developers,
> despite being the author of biplot.rda() I never got round to doing a
> triplot() generic and method...
>
> If you would care to offer some code it would be appreciated, otherwise
> I might get to take a look later in May.

Once my exams are graded, I'll take a look at the existing code and see
what I can do!

Cheers,

Tyler