[R] Loop over regression results

[Thierry Onkelinx]

Or even easier is you use lmList() from the nlme package

library(nlme)
data(iris)
regression.list <- lmList(Sepal.Width ~ Petal.Width | Species, data = iris)
summary(regression.list)
coef(regression.list)


Best regards,

Thierry

ir. Thierry Onkelinx
Instituut voor natuur- en bosonderzoek / Research Institute for Nature and
Forest
team Biometrie & Kwaliteitszorg / team Biometrics & Quality Assurance
Kliniekstraat 25
1070 Anderlecht
Belgium

To call in the statistician after the experiment is done may be no more
than asking him to perform a post-mortem examination: he may be able to say
what the experiment died of. ~ Sir Ronald Aylmer Fisher
The plural of anecdote is not data. ~ Roger Brinner
The combination of some data and an aching desire for an answer does not
ensure that a reasonable answer can be extracted from a given body of data.
~ John Tukey

2015-02-16 16:17 GMT+01:00 David L Carlson <dcarlson op tamu.edu>:

> Or for the slopes and t-values:
>
> > do.call(rbind, lapply(mod, function(x) summary(x)[["coefficients"]][2,]))
>             Estimate Std. Error  t value     Pr(>|t|)
> setosa     0.8371922  0.5049134 1.658091 1.038211e-01
> versicolor 1.0536478  0.1712595 6.152348 1.466661e-07
> virginica  0.6314052  0.1428938 4.418702 5.647610e-05
>
> David C
>
> -----Original Message-----
> From: R-help [mailto:r-help-bounces op r-project.org] On Behalf Of David L
> Carlson
> Sent: Monday, February 16, 2015 8:52 AM
> To: Ronald Kölpin; r-help op r-project.org
> Subject: Re: [R] Loop over regression results
>
> In R you would want to combine the results into a list. This could be done
> when you create the regressions or afterwards. To repeat your example using
> a list:
>
> data(iris)
> taxon <- levels(iris$Species)
> mod <- lapply(taxon, function (x) lm(Sepal.Width ~ Petal.Width,
>         data=iris, subset=Species==x))
> names(mod) <- taxon
> lapply(mod, summary)
> coeffs <- do.call(rbind, lapply(mod, coef, "[1"))
> coeffs
> #             (Intercept) Petal.Width
> # setosa        3.222051   0.8371922
> # versicolor    1.372863   1.0536478
> # virginica     1.694773   0.6314052
>
> -------------------------------------
> David L Carlson
> Department of Anthropology
> Texas A&M University
> College Station, TX 77840-4352
>
>
>
>
> -----Original Message-----
> From: R-help [mailto:r-help-bounces op r-project.org] On Behalf Of Ronald
> Kölpin
> Sent: Monday, February 16, 2015 7:37 AM
> To: r-help op r-project.org
> Subject: [R] Loop over regression results
>
> -----BEGIN PGP SIGNED MESSAGE-----
> Hash: SHA1
>
> Dear all,
>
> I have a problem when trying to present the results of several
> regression. Say I have run several regressions on a dataset and saved
> the different results (as in the mini example below). I then want to
> loop over the regression results in order so save certain values to a
> matrix (in order to put them into a paper or presentation).
>
> Aside from the question of how to access certain information stored by
> lm() (or printed by summary()) I can't seem to so loop over lm()
> objects -- no matter whether they are stored in a vector or a list.
> They are always evaluated immediately when called. I tried quote() or
> substitute() but that didn't work either as "Objects of type 'symbol'
> cannot be indexed."
>
> In Stata I would simply do something like
>
> forvalues k = 1/3 {
>  quietly estimates restore mod`k'
> // [...]
> }
>
> and I am looking for the R equivalent of that syntax.
>
> Kind regard and thanks
>
> RK
>
>
> attach(iris)
> mod1 <- lm(Sepal.Width ~ Petal.Width, data=iris, subset=Species=="setosa")
> mod2 <- lm(Sepal.Width ~ Petal.Width, data=iris,
> subset=Species=="versicolor")
> mod3 <- lm(Sepal.Width ~ Petal.Width, data=iris,
> subset=Species=="virginica")
>
> summary(mod1); summary(mod2); summary(mod3)
>
> mat <- matrix(data=NA, nrow=3, ncol=5,
>               dimnames=list(1:3, c("Model", "Intercept", "p(T > |T|)",
> "Slope", "R^2")))
>
> mods <- c(mod1, mod2, mod3)
>
> for(k in 1:3)
> {
>     mod <- mods[k]
>     mat[2,k] <- as.numeric(coef(mod))[1]
>     mat[3,k] <- as.numeric(coef(mod))[1]
> }
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> ______________________________________________
> R-help op r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.
>
> ______________________________________________
> R-help op r-project.org mailing list -- To UNSUBSCRIBE and more, see
> 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.
>

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