[R] "aliases" for R constructs?

[Simon Fear]

Some related suggestions:

1. instead of dataFrame[condition, ], use 

>>>>>>>>>>>  subset()  <<<<<<<<<<<

which has an inbuilt test for !is.na(condition). This function is 
not documented in the Introduction or cross-referenced 
by ?"[", so should be posted to this list at least once a week 
until everybody knows about it. (Sorry Martin M. that I still 
have not done what I promised re documentation. The ink has
faded so much on the sticky reminder that I can't read it
any more.)

2. consider using an editor with definable keyboard macros.
There's nothing quicker, or easier to debug, than plain old,
bottom level !is.na, but you can get there by typing F1 if you 
set it up that way.

3. I have a very old brown-covered book describing macros in
the S language (version 1? I don't have it to hand to check). 
When and why did they disappear? (Hoping John Chambers 
is reading this.)

> -----Original Message-----
> From: Thomas Lumley [mailto:tlumley at u.washington.edu]
> Sent: 20 October 2003 23:03
> To: Ted.Harding at nessie.mcc.ac.uk
> Cc: r-help at stat.math.ethz.ch
> Subject: Re: [R] "aliases" for R constructs?
> 
> 
> Security Warning:
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> ________________________________________________________________
> 
> On Mon, 20 Oct 2003 Ted.Harding at nessie.mcc.ac.uk wrote:
> 
> > Hi Folks,
> >
> > My recent response to Laura Quinn's query about matrix subsetting
> > reminded of a question.
> >
> > I wrote:
> >
> >   iDir <- ((Winds[,20]<45)|(Winds[,20]>315))&(!is.na(Winds[,20]))
> >
> > Now, I find "!is.na" a bit awkward to type, so I might prefer to
> > type it as "nis.na".
> >
> > While it is possible to define
> >
> >   nis.na <- function(x){ !is.na(x) }
> >
> > this involves a slight bloat of overhead in execution since 
> achieving
> > !is.na involves an extra layer of function call. So is it possible
> > to define an "alias" so that
> >
> >   nis.na(x)
> >
> > is _exactly_ equivalent to
> >
> >   !is.na(x)
> >
> 
> No, R doesn't have macros.  As R is interpreted, a macro wouldn't
> necessarily save you any execution time -- Lisp macros, IIRC, are only
> expanded at compile-time.
> 
> You can get most of the programming advantages of macros with 
> substitute
> and eval, but this is presumably slower rather than faster.
> 
> 
> 	-thomas
> 
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>  
 
Simon Fear 
Senior Statistician 
Syne qua non Ltd 
Tel: +44 (0) 1379 644449 
Fax: +44 (0) 1379 644445 
email: Simon.Fear at synequanon.com 
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