[R-sig-eco] vegan's ordistep function

[Olmo]

 Hi Carolina, it could be a syntaxis ommition indeed, I see a space
 that I think it must not be there, between < and the minus - ,
 (probably = is simpler but I use <- too):

> step.forward < - ordistep(rda(main ~ 1, data=second),
 scope=formula(RDA.all), direction="forward", pstep=1000)

> step.forward <- ordistep(rda(main ~ 1, data=second),
 scope=formula(RDA.all), direction="forward", pstep=1000)

 Check that, just in case.

Hope this helps,
Olmo.


El Sat, 4 Feb 2012 15:03:08 -0400
carolina monmany <acmonmany at gmail.com> escribió:
> Dear all,
> 
> I am running a redundancy analysis in vegan and I am using ordistep to
> perform a forward selection of variables in my model. I'm following
> Borcard et al. (2011) for this. I got stuck in one of the steps and
> couldn't find out why.
> 
> > RDA.all <- rda(main ~ ., data=second)
> > RDA.all
> Call: rda(formula = main ~ MeanAsp + SDAsp + MenaSlo + SDSlo + Urban +
> Treelines + TreeGroups +
> SolTress + IntermGrass + TallGrass + Highways + Canals + DistDCA +
> MeanTrackDens + SDTrackDens +
> MeanMagnetism, data = second)
> 
>                Inertia Proportion Rank
> Total         0.005999   1.000000
> Constrained   0.005999   1.000000    9
> Unconstrained 0.000000   0.000000    0
> Inertia is variance
> Some constraints were aliased because they were collinear (redundant)
> 
> Eigenvalues for constrained axes:
>      RDA1      RDA2      RDA3      RDA4      RDA5      RDA6      RDA7
>  RDA8      RDA9
> 4.421e-03 1.406e-03 8.930e-05 5.354e-05 1.413e-05 8.836e-06 4.612e-06
> 1.324e-06 3.500e-07
> 
> # And here's the problem,
> 
> > step.forward < - ordistep(rda(main ~ 1, data=second),
> scope=formula(RDA.all), direction="forward", pstep=1000)
> Error: object 'step.forward' not found
> 
> I hope it's a syntaxis ommition or error. Any clue?
> 
> Thanks a lot,
> 
> Carolina
>