Message-ID: <facbc0f4-33c4-4c06-2d43-37830d83211b@univ-reims.fr>
Date: 2016-05-23T11:43:07Z
From: Ivan Calandra
Subject: meaning of lm( y~., data=mydat ), is it a language feature, is it documented, is it supported?
In-Reply-To: <5742B0A3020000CB001550DE@smtp.medicine.umaryland.edu>
Hi John,
This is indeed documented, but you'll have to look at the function
formula():
?formula
Regarding the dot (.), here is the explanation from the help of formula():
"There are two special interpretations of . in a formula. The usual one
is in the context of a data argument of model fitting functions and
means ?all columns not otherwise in the formula?: see terms.formula. In
the context of update.formula, only, it means ?what was previously in
this part of the formula?."
HTH,
Ivan
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Ivan Calandra, PhD
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Le 23/05/2016 ? 13:26, John Sorkin a ?crit :
>
> The syntax
> mydat <- data.frame( y,x )
> fit1 <- lm( y~., data=mydat )
> appears to perform a multivariable regression of y on every non-y variable in the data frame mydat. I can not find this syntax (y~.) in R documentation. Is y~. a supported feature of the R language? Where can I find it documented? I would hate to write code that is dependent on a non-supported, non-documented language feature.
> Thank you,
> John
> John David Sorkin M.D., Ph.D.
> Professor of Medicine
> Chief, Biostatistics and Informatics
> University of Maryland School of Medicine Division of Gerontology and Geriatric Medicine
> Baltimore VA Medical Center
> 10 North Greene Street
> GRECC (BT/18/GR)
> Baltimore, MD 21201-1524
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