Re: cbind is not generic as claimed, omits labels where S has them (PR#239)

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Subject: Re: cbind is not generic as claimed, omits labels where S has them (PR#239)
From: Prof Brian D Ripley (ripley@stats.ox.ac.uk)
Date: Fri 06 Aug 1999 - 02:19:08 EST


Message-ID: <Pine.GSO.4.05.9908051705140.2936-100000@auk.stats>

On 5 Aug 1999, Peter Dalgaard BSA wrote:

> (1) The docs are clearly wrong (or perhaps rather, wishful thinking)

Sorry, but always the docs are right and the implementation wrong.
That's an axiom of professional computer programming (so I am told
by several ex-professional computer programmers.)

> (2) Cbind should be generic as in Splus
>
> (3) For the labels, one needs essentially to implement deparse.level
> or face the horrors of
> eval(substitute(cbind(a,b,deparse.level=2),list(a=rnorm(10),b=rnorm(10))))

Really? Or try a bit less hard? Getting the common cases right is not
too hard -- ts.union etc seem normally to be about right, and they have
simple code.

> (4) The dataframe special casing seems to be an evasion. The sticky
> bit is that one needs to dispatch on *any* argument. For Splus (3.4)
> compatibility, one has to check each argument for its class
> method, and if all arguments agree - in the sense that all the
> arguments that have class methods must have the same one, dispatch
> to that method. If they disagree, print error message and try
> default method.
>
> Whoever wrote the code seems to have decided that things would be
> easier if one assumed that the only method for cbind was
> cbind.data.frame...
>
> Note that by the above logic, if you make a cbind.ts, you can't
> cbind a time series to a data frame!

That's OK, as I can coerce a data frame to a ts, but in general I want to
cbind ts objects with non-trivial time bases.

I don't think documenting what we have is a good way out here....

-- 
Brian D. Ripley,                  ripley@stats.ox.ac.uk
Professor of Applied Statistics,  http://www.stats.ox.ac.uk/~ripley/
University of Oxford,             Tel:  +44 1865 272861 (self)
1 South Parks Road,                     +44 1865 272860 (secr)
Oxford OX1 3TG, UK                Fax:  +44 1865 272595

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