R devel - May 2004 - Buglet/omission in nls package (PR#6901)

Dear all,

I noticed the following under R 1.8.1 (when nls was still a separate
package) but the same problem occurs under R 1.9.0 (where most (all?)
of nls is now in the stats package):
> data(Puromycin)
> fm <- nls(rate~SSmicmen(conc,b0,b1), Puromycin, subset =
state=="treated")
> coef(summary(fm))
NULL

The problem seems to be that summary.nls uses the name "parameters"
instead of the name "coefficients" for the matrix with the estimates,
standard errors, t values and p values:
> summary(fm)$parameters
       Estimate  Std. Error   t value     Pr(>|t|)
b0 212.68370728 6.947153198 30.614512 3.241160e-11
b1   0.06412123 0.008280944  7.743227 1.565136e-05

Thus, coef.default fails on an object of class "summary.nls".

Possible fixes:
1) Rename that part of the summary.nls structure from parameters to
   coefficients  (not sure if that breaks something else); or
2) Write a coef.summary.nls method that returns the structure
   parameter from a summary.nls object passed to it.

Cheers,

        Berwin

--please do not edit the information below--

Version:
 platform = i686-pc-linux-gnu
 arch = i686
 os = linux-gnu
 system = i686, linux-gnu
 status = 
 major = 1
 minor = 9.0
 year = 2004
 month = 04
 day = 12
 language = R

Search Path:
 .GlobalEnv, package:methods, package:stats, package:graphics, package:utils,
Autoloads, package:base

Berwin,

No one has said the coef() will work on a summary object, but it would be 
nice if it did where appropriate.

I've added an summary.nls method for 2.0.0.

Brian

On Fri, 21 May 2004 berwin@maths.uwa.edu.au wrote:
> Dear all,
> 
> I noticed the following under R 1.8.1 (when nls was still a separate
> package) but the same problem occurs under R 1.9.0 (where most (all?)
> of nls is now in the stats package):
`all of nls', indeed.
> > data(Puromycin)
> > fm <- nls(rate~SSmicmen(conc,b0,b1), Puromycin, subset =
state=="treated")
> > coef(summary(fm))
> NULL
> 
> The problem seems to be that summary.nls uses the name
"parameters"
> instead of the name "coefficients" for the matrix with the
estimates,
> standard errors, t values and p values:
> 
> > summary(fm)$parameters
>        Estimate  Std. Error   t value     Pr(>|t|)
> b0 212.68370728 6.947153198 30.614512 3.241160e-11
> b1   0.06412123 0.008280944  7.743227 1.565136e-05
> 
> Thus, coef.default fails on an object of class "summary.nls".
> 
> Possible fixes:
> 1) Rename that part of the summary.nls structure from parameters to
>    coefficients  (not sure if that breaks something else); or
> 2) Write a coef.summary.nls method that returns the structure
>    parameter from a summary.nls object passed to it.
> 
> Cheers,
> 
>         Berwin
> 
> --please do not edit the information below--
> 
> Version:
>  platform = i686-pc-linux-gnu
>  arch = i686
>  os = linux-gnu
>  system = i686, linux-gnu
>  status = 
>  major = 1
>  minor = 9.0
>  year = 2004
>  month = 04
>  day = 12
>  language = R
> 
> Search Path:
>  .GlobalEnv, package:methods, package:stats, package:graphics,
package:utils, Autoloads, package:base
> 
> ______________________________________________
> R-devel@stat.math.ethz.ch mailing list
> https://www.stat.math.ethz.ch/mailman/listinfo/r-devel
> 
> 
-- 
Brian D. Ripley,                  ripley@stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272866 (PA)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595