Re: [Rd] c.factor

From: Marc Schwartz <marc_schwartz_at_comcast.net>
Date: Wed 15 Nov 2006 - 14:36:40 GMT

On Wed, 2006-11-15 at 12:51 +0000, Matthew Dowle wrote:

<snip>

> I have a solution which works for me, and I have contributed it. One
> other person has shown some interest, and taken it further to work with
> multiple arguments which looks like a nice improvement.

Just for clarification, my interest was only to provide an alternative that provided for a more generic approach, at least in a narrow application, not that I was advocating it's need. Perhaps I should have called the function something else to avoid confusion and that was my error. Needless to say that we both ignored the overhead of error checking related functionality.

In my 5 odd years of using R, I would have to acknowledge that I have yet to have a need for this type of function (save within the context of merge() and rbind()). That does not mean that I have exhausted the possibilities over that time, but that in the course of meeting my particular requirements, it has yet to come up.

I would agree with Prof. Ripley's comments, that one needs to be quite careful in manipulating factors in this fashion, not the least of which would be ordered factors, which have not been considered here and could/would introduce their own idiosyncrasies in this context.

If something like this gets implemented (ie. concat()) one would need to fully understand the behavioral subtleties and the nature of the results, lest naive users find themselves in the potential presence of cascading errors.

HTH, Marc



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