On Sun, 28 Jan 2001 baron@cattell.psych.upenn.edu wrote:
> Full_Name: Jonathan Baron
> Version: 1.2.1
> OS: Linux
> Submission from: (NULL) (151.197.202.231)
>
>
> The following gives an error message:
> > nls(doit[2,] ~ 7/(1 + exp(a*efft[2,])),start=c(a=-.1))
> Error in as.name(varName) : attempt to use zero-length variable name
>
> The following runs fine:
> > nls(doit.vm ~ 7/(1 + exp(a*efft.vm)),start=c(a=-.1))
>
> This happens even though doit.vm and doit[2,] are identical (and efft[])
>
Looks like a problem (?) with all.vars():
temp <- matrix(1:4, 2)
all.vars(temp ~ 3) # OK
[1] "temp"
all.vars(temp[1, ] ~ 3) # Here is the problem.
[1] "temp" ""
all.vars(temp[1, TRUE] ~ 3) # works again
[1] "temp"
If this is expected (?), because of an implicitly given empty variable
name ([1, ThisOne]) for example, nls() has to be fixed:
Just insert after the lines
varNames <- varNames[is.na(match(varNames, names(start),
nomatch = NA))]
the line
varNames <- varNames[varNames != ""]
Uwe Ligges
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