[R] nlsList (nlme) error

[Rick DeShon]

Hi All.

I'm trying to run nlsList an getting an error that makes no sense to
me.  I have accuracy and reaction time data over many trials for each
person (id)

When I use nlsList code that is virtually identical to the example in
the doc file I get the following error.  I've tried everything I could
think of and can't get around it.  Any ideas what I'm doing wrong?
**************
      fm.nls<-nlsList(RT ~ SSasymp(trial, Asym, R0, lrc) ,
                      data = df.group,
                      na.action="na.exclude",
                     start = c(Asym = 550, R0 = 770, rc =-2.5))

     "Error in nlsList.formula(RT ~ SSasymp(trial, Asym, R0, lrc),
data = df.group,  :
      Data must be a groupedData object if formula does not include groups"
***************

Here's the first 10 records of my data:

> df.group[1:10,]
Grouped Data: RT ~ trial | id
      id trial ACC   RT block
1.1   1     1   1 1111     1
2.1   2     1   0   NA     1
3.1   3     1   1 1309     1
4.1   4     1   1  544     1
5.1   5     1   1  654     1
6.1   6     1   0   NA     1
7.1   7     1   1  441     1
8.1   8     1   1  882     1
9.1   9     1   1 1097     1
10.1 10     1   1  898     1


The data are clearly grouped.  Just to be sure....

str(df.group)
Classes 'nfnGroupedData', 'nfGroupedData', 'groupedData' and
'data.frame':	15480 obs. of  5 variables:
 $ id   : Ord.factor w/ 43 levels "31"<"8"<"30"<..: 41 11 33 22 4 27 5
2 37 19 ...
 $ trial: int  1 1 1 1 1 1 1 1 1 1 ...
 $ ACC  : int  1 0 1 1 1 0 1 1 1 1 ...
 $ RT   : int  1111 NA 1309 544 654 NA 441 882 1097 898 ...
 $ block: int  1 1 1 1 1 1 1 1 1 1 ...
 - attr(*, "formula")=Class 'formula' length 3 RT ~ trial | id
  .. ..- attr(*, ".Environment")=<R_GlobalEnv>
 - attr(*, "FUN")=function (x)
 - attr(*, "order.groups")= logi TRUE

Thanks!

Rick DeShon

> version
               _
platform       i386-apple-darwin8.10.1
arch           i386
os             darwin8.10.1
system         i386, darwin8.10.1
status
major          2
minor          6.1
year           2007
month          11
day            26
svn rev        43537
language       R
version.string R version 2.6.1 (2007-11-26)