Yes Dimitri that's what I mean!
Something like this?
for(i in levels(c)) { lm(a ~ b * c , data=mydataset)}
And what about to see the output?
Thanks!
> Date: Fri, 20 May 2011 09:46:08 -0400
> Subject: Re: [R] [r] regression coefficient for different factors
> From: dimitri.liakhovit...@gmail.com
> To: nutini.france...@gmail.com
> CC: rb...@atsu.edu; r-help@r-project.org
>
> Francesco, do you just want a separate regression for each level of
> your factor c?
> You could write a loop - looping through levels of c:
>
> for(i in levels(c)){
> select your data here and write a regression formula
> }
>
> On Fri, May 20, 2011 at 9:39 AM, Francesco Nutini
> <nutini.france...@gmail.com> wrote:
> >
> > Thanks for your reply,
> >
> > ?summary produce a multiple r2.
> > My dataset il similar to this one:
> >
> >> a b c
> >> 1 -1.4805676 0.9729927 x
> >> 2 1.5771695 0.2172974 x
> >> 3 -0.9567445 0.5205087 x
> >> 4 -0.9200052 0.8279428 z
> >> 5 -1.9976421 0.9641110 z
> >> 6 -0.2722960 0.6318801 y
> >
> > So, I would like to know the r2 for a~b for every factors levels.
> > Off course I can made the regression separately for every factors, but my
> > dataset have 68 factors...
> >
> > ----------
> > Francesco Nutini
> > PhD student
> > CNR-IREA (Institute for Electromagnetic Sensing of the Environment)
> > Milano, Italy
> >
> > > From: rb...@atsu.edu
> >> To: nutini.france...@gmail.com; r-help@r-project.org
> >> Subject: Re: [R] [r] regression coefficient for different factors
> >> Date: Fri, 20 May 2011 08:07:59 -0500
> >>
> >> ?summary
> >>
> >> produces r^2 in 2nd to last line, as in,
> >> > set.seed(12); a=rnorm(100); b = runif(100); c = factor(rep(c('No',
> >> > 'Yes'),50)); df = data.frame(a,b,c)
> >> > head(df)
> >> a b c
> >> 1 -1.4805676 0.9729927 No
> >> 2 1.5771695 0.2172974 Yes
> >> 3 -0.9567445 0.5205087 No
> >> 4 -0.9200052 0.8279428 Yes
> >> 5 -1.9976421 0.9641110 No
> >> 6 -0.2722960 0.6318801 Yes
> >> > mod = lm(a ~ b*c)
> >> > summary(mod)
> >>
> >> Call:
> >> lm(formula = a ~ b * c)
> >>
> >> Residuals:
> >> Min 1Q Median 3Q Max
> >> -1.8196 -0.4754 -0.0246 0.5585 2.0941
> >>
> >> Coefficients:
> >> Estimate Std. Error t value Pr(>|t|)
> >> (Intercept) 0.2293 0.2314 0.991 0.324
> >> b -0.4226 0.3885 -1.088 0.280
> >> cYes 0.1578 0.3202 0.493 0.623
> >> b:cYes -0.5878 0.5621 -1.046 0.298
> >>
> >> Residual standard error: 0.8455 on 96 degrees of freedom
> >> Multiple R-squared: 0.07385, Adjusted R-squared: 0.04491
> >> F-statistic: 2.552 on 3 and 96 DF, p-value: 0.0601
> >>
> >> ------------------------------------------
> >> Robert W. Baer, Ph.D.
> >> Professor of Physiology
> >> Kirksville College of Osteopathic Medicine
> >> A. T. Still University of Health Sciences
> >> 800 W. Jefferson St.
> >> Kirksville, MO 63501
> >> 660-626-2322
> >> FAX 660-626-2965
> >>
> >>
> >> --------------------------------------------------
> >> From: "Francesco Nutini" <nutini.france...@gmail.com>
> >> Sent: Friday, May 20, 2011 4:17 AM
> >> To: "[R] help" <r-help@r-project.org>
> >> Subject: [R] [r] regression coefficient for different factors
> >>
> >> >
> >> > Dear R-helpers,
> >> >
> >> > In my dataset I have two continuous variable (A and B) and one factor.
> >> > I'm investigating the regression between the two variables usign the
> >> > command
> >> > lm(A ~ B, ...)
> >> > but now I want to know the regression coefficient (r2) of A vs. B for
> >> > every factors.
> >> > I know that I can obtain this information with excel, but the factor have
> >> > 68 levels...maybe [r] have a useful command.
> >> >
> >> > Thanks,
> >> >
> >> > Francesco Nutini
> >> >
> >> > [[alternative HTML version deleted]]
> >> >
> >> > ______________________________________________
> >> > R-help@r-project.org mailing list
> >> > 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.
> >> >
> >
> > [[alternative HTML version deleted]]
> >
> > ______________________________________________
> > R-help@r-project.org mailing list
> > 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.
> >
>
>
>
> --
> Dimitri Liakhovitski
> Ninah Consulting
> www.ninah.com
[[alternative HTML version deleted]]
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