That was the mistake. Now it worked. Thanks a lot, Roman and Olmo and
thanks for the recommendation on the code editor!

Carolina

2012/2/5 Olmo <ulmusnigra@yahoo.es>

>  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@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
> >
>
>
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-- 
---------------------------
A. CAROLINA MONMANY
Universidad de Puerto Rico
Departamento de Biologia - CN 235
POBOX 23360
San Juan, Puerto Rico 00931-3360
Tel: +1 787 764 0000 x2847
Fax: +1 787 764 2610

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