Re: [Rd] scale(x, center=FALSE) (PR#14219)

From: Ben Bolker <bolker_at_ufl.edu>
Date: Fri, 12 Mar 2010 13:29:44 -0500

  I'm resending this after a week ... I really don't want to nag, but I also would not like to see this sink below the waves.

  Is there a preferred protocol for requesting comments without nagging too much? I would add a comment to 14219 (and was curious to see whether it was rejected) ... I went to bugzilla, and bug 14219 doesn't seem to exist any more -- either as open or as closed -- don't know if it got lost, or thrown away, when the bug system migrated?

   cheers
     Ben Bolker

 [re: behavior of scale() when center=FALSE and scale=TRUE]

> Again, I agree with you that the behavior is not optimal, but it is
> very hard to make changes in R when the behavior is sub-optimal rather
> than actually wrong (by some definition). R-core is very conservative
> about changes that break backward compatibility; I would like it if they
> chose to change the function to use standard deviation rather than
> root-mean-square, but I doubt it will happen (and it would break things
> for any users who are relying on the current definition).

[snip]

> I have attached a patch
> file (and append the information below as well) that changes "standard
> deviation" back to "root mean square" and is much more explicit about
> this issue ... I hope R-core will jump in, critique it, and possibly use
> it in some form to improve (?) the documentation ...
>
> [PS: I have written that the scaling is equivalent to sd() "if and
> only if" centering was done. Technically it would also be equivalent if
> the column already had zero mean ...]
>


 (Bump re: suggested update to scale.Rd . Is this under consideration? I'll stop pestering if it's considered unacceptable, just don't want it to vanish without a trace ...)

-- 
Ben Bolker
Associate professor, Biology Dep't, Univ. of Florida
bolker_at_ufl.edu / people.biology.ufl.edu/bolker
GPG key: people.biology.ufl.edu/bolker/benbolker-publickey.asc


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