[R] mlogit is not an S4 object error

[Steve_Friedman at nps.gov]

Achim  - Everyone

Yes, I did exactly as you've suggested.  I did the analysis over on both my
windows XP machine and on my Linux machine.

It worked correctly.  I don't recall which other packages I installed the
first time, but there was a conflict.

Thanks you for the attention and the great replies.

Steve


Steve Friedman Ph. D.
Spatial Statistical Analyst
Everglades and Dry Tortugas National Park
950 N Krome Ave (3rd Floor)
Homestead, Florida 33034

Steve_Friedman at nps.gov
Office (305) 224 - 4282
Fax     (305) 224 - 4147


                                                                           
             Achim Zeileis                                                 
             <Achim.Zeileis at ui                                             
             bk.ac.at>                                                  To 
                                       Steve_Friedman at nps.gov              
             02/24/2010 04:20                                           cc 
             PM                        r-help at r-project.org                
                                                                   Subject 
                                       Re: [R] mlogit  is not an S4 object 
                                       error                               
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           
                                                                           




On Wed, 24 Feb 2010, Steve_Friedman at nps.gov wrote:

>
> Hello,
>
> I've been getting the following error  when using the mlogit function
from
> the mlogit package
>
> This is one of the examples provided in the Package "mlogit" January 27,
> 2010 description
>
> data("Fishing", package="mlogit")
> Fish <- mlogit.data(Fishing, varying = c(4:11), shape="wide",
> choice="mode")
> summary(mlogit(mode ~ pr + ca - 1, data = Fish))
>
>
> Call:
> Error in deparse(object at call) :
>  trying to get slot "call" from an object (class "mlogit") that is not an
> S4 object
>
> I'm running on Windows XP  R 2.10.1
>
> Does anyone have any ideas why this is failing ?

I cannot replicate this problem. I get the desired result (see below).
This is also unlikely to be a problem in the package itself because the
examples are checked daily on CRAN, see
   http://CRAN.R-project.org/web/checks/check_results_mlogit.html

My guess is that you have loaded some other package (other than "mlogit")
that defines an S4 generic for summary() that somehow messes up the
dispatch for mlogit. Please try to reinstall the package and run the
package in a fresh R session to check whether the problem persists.

Best,
Z


R> library("mlogit")
Loading required package: Formula
Loading required package: statmod
R> data("Fishing", package="mlogit")
R>  Fish <- mlogit.data(Fishing, varying = c(4:11), shape="wide",
+  choice="mode")
R>  summary(mlogit(mode ~ pr + ca - 1, data = Fish))

Call:
mlogit(formula = mode ~ pr + ca - 1, data = Fish, method = "nr",
     print.level = 0)

Frequencies of alternatives:
   beach    boat charter    pier
0.11337 0.35364 0.38240 0.15059

nr method
6 iterations, 0h:0m:0s
g'(-H)^-1g = 7.22E-11
optimum reached

Coefficients :
      Estimate Std. Error t-value  Pr(>|t|)
pr -0.0204765  0.0012231 -16.742 < 2.2e-16 ***
ca  0.9530985  0.0894134  10.659 < 2.2e-16 ***
---
Signif. codes:  0 '***' 0.001 '**' 0.01 '*' 0.05 '.' 0.1 ' ' 1

Log-Likelihood: -1312



> Thanks
> Steve
>
> Steve Friedman Ph. D.
> Spatial Statistical Analyst
> Everglades and Dry Tortugas National Park
> 950 N Krome Ave (3rd Floor)
> Homestead, Florida 33034
>
> Steve_Friedman at nps.gov
> Office (305) 224 - 4282
> Fax     (305) 224 - 4147
>
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> R-help at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-help
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>