From wdunlap at tibco.com  Thu Jan  5 21:56:30 2012
From: wdunlap at tibco.com (William Dunlap)
Date: Thu, 5 Jan 2012 20:56:30 +0000
Subject: [Rd] delete.response leaves response in attribute dataClasses
In-Reply-To: <CAErODj9Aibpb4M=xq9+hHKw6Qurphxb2O7nb4A8x=F3UxPZLgA@mail.gmail.com>
References: <CAErODj9Aibpb4M=xq9+hHKw6Qurphxb2O7nb4A8x=F3UxPZLgA@mail.gmail.com>
Message-ID: <E66794E69CFDE04D9A70842786030B932574D6@PA-MBX03.na.tibco.com>

I had noticed the same thing but figured that most
people (writers of predict methods) would be looking
up entries in dataClasses by name and not by position,
since predict's newdata argument need not have entries
in the same order as the data used to fit the model.
Hence the extra entry would not noticed (nor would it be
missed if it were omitted).

Bill Dunlap
Spotfire, TIBCO Software
wdunlap tibco.com 

> -----Original Message-----
> From: r-devel-bounces at r-project.org [mailto:r-devel-bounces at r-project.org] On Behalf Of Paul Johnson
> Sent: Thursday, January 05, 2012 12:27 PM
> To: R Devel List
> Subject: [Rd] delete.response leaves response in attribute dataClasses
> 
> I posted this one as an R bug
> (https://bugs.r-project.org/bugzilla3/show_bug.cgi?id=14767), but
> Prof. Ripley says I'm premature, and I should raise the question here.
> 
> Here's the behavior I assert is a bug:
> The output from delete.response on a terms object alters the formula
> by removing the dependent variable. It removes the response from the
> "variables" attribute and it changes the response attribute from 1 to
> 0.  The response is removed from "predvars"
> 
> But it leaves the name of the dependent variable first in the in
> "dataClasses".  It caused an unexpected behavior in my code, so (as
> usual) the bug may be mine, but in my heart, I believe it belongs to
> delete.response.
> 
> To illustrate, here's a terms object from a regression.
> 
> > tt
> y ~ x1 * x2 + x3 + x4
> attr(,"variables")
> list(y, x1, x2, x3, x4)
> attr(,"factors")
>    x1 x2 x3 x4 x1:x2
> y   0  0  0  0     0
> x1  1  0  0  0     1
> x2  0  1  0  0     1
> x3  0  0  1  0     0
> x4  0  0  0  1     0
> attr(,"term.labels")
> [1] "x1"    "x2"    "x3"    "x4"    "x1:x2"
> attr(,"order")
> [1] 1 1 1 1 2
> attr(,"intercept")
> [1] 1
> attr(,"response")
> [1] 1
> attr(,".Environment")
> <environment: R_GlobalEnv>
> attr(,"predvars")
> list(y, x1, x2, x3, x4)
> attr(,"dataClasses")
>         y        x1        x2        x3        x4
> "numeric" "numeric" "numeric" "numeric" "numeric"
> 
> Now observe that delete.response removes the response from all
> attributes except dataClasses.
> 
> > delete.response(tt)
> ~x1 * x2 + x3 + x4
> attr(,"variables")
> list(x1, x2, x3, x4)
> attr(,"factors")
>    x1 x2 x3 x4 x1:x2
> x1  1  0  0  0     1
> x2  0  1  0  0     1
> x3  0  0  1  0     0
> x4  0  0  0  1     0
> attr(,"term.labels")
> [1] "x1"    "x2"    "x3"    "x4"    "x1:x2"
> attr(,"order")
> [1] 1 1 1 1 2
> attr(,"intercept")
> [1] 1
> attr(,"response")
> [1] 0
> attr(,".Environment")
> <environment: R_GlobalEnv>
> attr(,"predvars")
> list(x1, x2, x3, x4)
> attr(,"dataClasses")
>         y        x1        x2        x3        x4
> "numeric" "numeric" "numeric" "numeric" "numeric"
> 
> 
> pj
> 
> --
> Paul E. Johnson
> Professor, Political Science
> 1541 Lilac Lane, Room 504
> University of Kansas
> 
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel



[Rd] delete.response leaves response in attribute dataClasses
William Dunlap