R help - Sep 2002 - Problem with leaps (long)

I am generating a bunch of examples for my students and when I type

            R BATCH demo10.R

(file demo10.R reproduced below) I get an error:

------------- Error message ------
> plot(mods$size,mods$Cp,
+      main="Cp versus talla modelos",
+      xlab=expression(p),
+      ylab=expression(C[p]))
Error in plot.window(xlim, ylim, log, asp, ...) : 
	need finite ylim values
In addition: Warning messages: 
1: no finite arguments to min; returning Inf 
2: no finite arguments to max; returning -Inf 
Execution halted
----------------------------------

On looking at object "mods", I see that indeed mods$Cp is full of
NaNs.

Exactly the same file worked last year. What is more strange, if I
type or paste the commands interactively, I get plausible Cp values in
mods$Cp. It is only in BATCH that the thing goes stray.

----------  File demo10.R up to the error point ---------
library(MASS)
data(UScrime) 
UScrime[1:3,]
attach(UScrime)                       

completo <- lm(y ~ . , data=UScrime)
summary(completo)

library(leaps)
X    <- as.matrix(UScrime[,-16])
y    <- UScrime[,16]
mods <- leaps(x=X,y=y,method="Cp") 

postscript(file="demo10.eps",
           horizontal=FALSE,
           width=5,height=9)
par(mfrow=c(2,1))
plot(mods$size,mods$Cp,
     main="Cp versus talla modelos",
     xlab=expression(p),
     ylab=expression(C[p]))
--------------------------------------------------

While on the same topic, the help on line advocates the use of function
regsubsets, which is said to improve on leaps on several ways. However,
I see no way to select different criteria (Cp, R2, adjR2) in said
function. 

I am using R 1.5.1 under Debian/Linux 3.0 (kernel 2.4.18, gcc -v
reports "gcc version 2.95.4 20011002", if that matters).

Many thanks for any help. 

ft.
-- 
Fernando TUSELL                                e-mail:
Departamento de Econometr?a y Estad?stica           etptupaf at bs.ehu.es 
Facultad de CC.EE. y Empresariales             Tel:   (+34)94.601.3733
Avenida Lendakari Aguirre, 83                  Fax:   (+34)94.601.3754
E-48015 BILBAO  (Spain)                        Secr:  (+34)94.601.3740
PGP: finger etptupaf at bsdx01.bs.ehu.es          http://etdx01.bs.ehu.es
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On Wed, 11 Sep 2002, F. Tusell wrote:
> On looking at object "mods", I see that indeed mods$Cp is full of
NaNs.
>
> Exactly the same file worked last year. What is more strange, if I
> type or paste the commands interactively, I get plausible Cp values in
> mods$Cp. It is only in BATCH that the thing goes stray.
Strange. I'll look at this.
>
> While on the same topic, the help on line advocates the use of function
> regsubsets, which is said to improve on leaps on several ways. However,
> I see no way to select different criteria (Cp, R2, adjR2) in said
> function.
You don't need to select different criteria in fitting.  You always get
the best model(s) of each size, and within a model size the criteria are
all equivalent to the residual sum of squares.  The summary() method
computes all these criteria, so you can use whichever you like.

The leaps() function works the same way, it's just that it doesn't even
report the other criteria.  In the actual Fortran it's all just residual
sums of squares.

	-thomas

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