Re: [R] meaning of lm( y~., data=mydat ), is it a language feature, is it documented, is it supported?

[peter dalgaard]

> On 23 May 2016, at 13:43 , Ivan Calandra  wrote:
> 
> 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’."

Actually, it is debatable which one of those deserve to be called "usual". Once 
upon a time, in the heyday of John Tukey, it might have been usual to have data 
set of a few hundred rows and, like, a dozen columns, exactly one of which 
being the response. Not so much these days, I'd say.

-pd

> 
> HTH,
> Ivan
> 
> --
> Ivan Calandra, PhD
> Scientific Mediator
> University of Reims Champagne-Ardenne
> GEGENAA - EA 3795
> CREA - 2 esplanade Roland Garros
> 51100 Reims, France
> +33(0)3 26 77 36 89
> ivan.calan...@univ-reims.fr
> --
> https://www.researchgate.net/profile/Ivan_Calandra
> https://publons.com/author/705639/
> 
> Le 23/05/2016 à 13:26, John Sorkin a écrit :
>>  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
>> (Phone) 410-605-7119
>> (Fax) 410-605-7913 (Please call phone number above prior to faxing)
>> 
>> Confidentiality Statement:
>> This email message, including any attachments, is for ...{{dropped:8}}
> 
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-- 
Peter Dalgaard, Professor,
Center for Statistics, Copenhagen Business School
Solbjerg Plads 3, 2000 Frederiksberg, Denmark
Phone: (+45)38153501
Office: A 4.23
Email: pd@cbs.dk  Priv: pda...@gmail.com

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Re: [R] meaning of lm( y~., data=mydat ), is it a language feature, is it documented, is it supported?

[Bert Gunter]

It's about formula syntax, so ?formula documents it.

Bert

On Monday, May 23, 2016, John Sorkin  wrote:

>
> 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
> (Phone) 410-605-7119
> (Fax) 410-605-7913 (Please call phone number above prior to faxing)
>
> Confidentiality Statement:
> This email message, including any attachments, is for ...{{dropped:25}}

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Re: [R] meaning of lm( y~., data=mydat ), is it a language feature, is it documented, is it supported?

[Kenneth Knoblauch]

John Sorkin  grecc.umaryland.edu> writes:
> 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
> (Phone) 410-605-7119
> (Fax) 410-605-7913
> 

How about section 11.5 of An Introduction to R?

-- 
Kenneth Knoblauch
Inserm U1208
Stem-cell and Brain Research Institute
18 avenue du Doyen Lépine
69500 Bron
France
tel: +33 (0)4 72 91 34 77
fax: +33 (0)4 72 91 34 61
portable: +33 (0)6 84 10 64 10
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Re: [R] meaning of lm( y~., data=mydat ), is it a language feature, is it documented, is it supported?

[Duncan Murdoch]

On 23/05/2016 7:26 AM, John Sorkin wrote:


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.


It is documented in the Introduction to R manual (hidden in section 
11.5, "Updating fitted models"), and in ?formula, which ?lm refers to.


Duncan Murdoch

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Re: [R] meaning of lm( y~., data=mydat ), is it a language feature, is it documented, is it supported?

[Ivan Calandra]

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

--
Ivan Calandra, PhD
Scientific Mediator
University of Reims Champagne-Ardenne
GEGENAA - EA 3795
CREA - 2 esplanade Roland Garros
51100 Reims, France
+33(0)3 26 77 36 89
ivan.calan...@univ-reims.fr
--
https://www.researchgate.net/profile/Ivan_Calandra
https://publons.com/author/705639/

Le 23/05/2016 à 13:26, John Sorkin a écrit :
  
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
(Phone) 410-605-7119
(Fax) 410-605-7913 (Please call phone number above prior to faxing)

Confidentiality Statement:
This email message, including any attachments, is for ...{{dropped:8}}


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[R] meaning of lm( y~., data=mydat ), is it a language feature, is it documented, is it supported?

[John Sorkin]

 
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
(Phone) 410-605-7119
(Fax) 410-605-7913 (Please call phone number above prior to faxing) 

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