[R] matrix (column-wise) multiple regression

[Gabor Grothendieck]

You can look at the components of the output using str and pick out
what you want
using $ and attr.

idx <- 1:2
z <- lm(as.matrix(iris[idx]) ~., iris[-idx])
str(z)
str(summary(z))

On Nov 23, 2007 1:10 PM, Morgan Hough <mhough at fmrib.ox.ac.uk> wrote:
> Hi Gabor,
>
> Thanks for your reply. I have it working now. A couple of follow-ups if
> I may.
>
> I have a shell script parsing the output to find the brain areas where
> there is a significant effect of diagnosis but its a bit of a hack. I
> was wondering whether there are R specific tools for parsing/summarizing
> this kind of output.
>
> Can I apply multiple comparison corrections via lm() or do I need to
> apply something on the model output from lm() after?
>
> Thanks again for your time.
>
> Cheers,
>
> -Morgan
>
>
> Gabor Grothendieck wrote:
> > Perhaps something like this:
> >
> >
> >> idx <- 1:2
> >> lm(as.matrix(iris[idx]) ~., iris[-idx])
> >>
> >
> > Call:
> > lm(formula = as.matrix(iris[idx]) ~ ., data = iris[-idx])
> >
> > Coefficients:
> >                    Sepal.Length  Sepal.Width
> > (Intercept)         3.682982      3.048497
> > Petal.Length        0.905946      0.154676
> > Petal.Width        -0.005995      0.623446
> > Speciesversicolor  -1.598362     -1.764104
> > Speciesvirginica   -2.112647     -2.196357
> >
> >
> >
> > On Nov 23, 2007 10:09 AM, Morgan Hough <mhough at fmrib.ox.ac.uk> wrote:
> >
> >> Hi there,
> >>
> >> I am analyzing a table of brain volume measures where each brain area
> >> (183 of them) is a column with a label and volume values. I have another
> >> table of explanatory variables (age, gender, diagnosis and
> >> IntraCranialVol) that I have been using to model the brain volume
> >> differences. I have been doing this for single volume measures with no
> >> difficulties but I have been unable to apply this across the whole set
> >> of brain areas. If I try:
> >>
> >> lm(y.df, x.df)
> >> Error in eval(expr, envir, enclos) : object "Left_Lateral_Ventricle" not
> >> found
> >>
> >> Left_Lateral_Ventricle happens to be the first column label. Does this
> >> not work with tables? I have been unable to find any examples.
> >>
> >> Would you recommend another approach if I was doing this again. The
> >> number of columns (brain areas) depends on the parcellation strategy we
> >> use so I will probably be reforming these tables again and again. I
> >> would like the simplest way to analyze all the brain areas and find
> >> where there are significant differences driven mainly by the diagnosis
> >> factor.
> >>
> >> Thanks in advance for your time.
> >>
> >> Cheers,
> >>
> >> -Morgan
> >>
> >> ---------------------------------------------------------------------------
> >> Morgan Hough,
> >> D.Phil. Student,
> >> Oxford University FMRIB Centre
> >>
> >> FMRIB, JR Hospital, Headington, Oxford  OX3 9DU, UK
> >> +44 (0) 1865 222466  (fax 222717)
> >> mhough at fmrib.ox.ac.uk    http://www.fmrib.ox.ac.uk/~mhough
> >>
> >> ______________________________________________
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> >> https://stat.ethz.ch/mailman/listinfo/r-help
> >> PLEASE do read the posting guide http://www.R-project.org/posting-guide.html
> >> and provide commented, minimal, self-contained, reproducible code.
> >>
> >>
>
>