[R] Package manual examples - 'unexpected$undefined' errors
murdoch at stats.uwo.ca
Mon Jul 30 16:35:49 CEST 2007
David Pain wrote:
> Trying out an unfamiliar package, the natural thing is to use the examples
> given in the package's manual - hopefully, the writers of the package
> wouldn't include examples which didn't work!
> Recently, though, I've been getting 'unexpected$undefined' error messages
> when doing this, despite having copy/pasted the text from the manual (taking
> out hard breaks on the way).
> Moreover, I've had error messages for commands which I've previously had
> work fine.
> For instance, this from Zelig
> z.out < zelig(vote ~ race + educate, model = "logit", data = turnout)
> has at different times worked fine and thrown up the error message.
> Any help gratefully received.
> [[alternative HTML version deleted]]
It's hard to say exactly what's going wrong, but a guess is that in your
workspace you have an object which is somehow conflicting with an object
in the package. Try starting R with the --vanilla command line option
and if the errors go away, that's why.
I don't know whether this applies to the Zelig package, but packages
that don't define namespaces are fragile in that their internal
functions can be masked by same-named functions in your workspace. Even
if the package does have a namespace, you can mask functions from it
that you call: for example, if you had a function called zelig (perhaps
because you used fix(zelig) to make a small change to the existing one),
your line above would call yours, not the original.
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