R devel - Feb 2006 - Arguments of 'transform'

If you would like a 10 second R puzzle, you might like to think about
this one:

> g <- expand.grid(long = 130:140, lat = -(10:25))
> gp <- transform(g, x = long, y = lat)
Error in transform(g, x = long, y = lat) : 
        object "long" not found


I don't expect this hasn't come up before, but I can't find mention
of
it.  I suggest that to minimise this little stumbling block for
beginners (and others) we either

	change the name of the principal argument in transform from 'x'
to, say '.x' (or even 'data' as it is in 'with' for
example)  OR

	at least put a note in the help file for 'transform' in the
'Detalis' section to say
     
	*** NOTE: The only tag name unavailable to be used is 'x'. ***

Just another little seed.

Bill.

Bill Venables, 
CMIS, CSIRO Laboratories, 
PO Box 120, Cleveland, Qld. 4163 
AUSTRALIA 
Office Phone (email preferred): +61 7 3826 7251 
Fax (if absolutely necessary):    +61 7 3826 7304 
Mobile (rarely used):                +61 4 1963 4642 
Home Phone:                          +61 7 3286 7700 
mailto:Bill.Venables at csiro.au 
http://www.cmis.csiro.au/bill.venables/

<Bill.Venables at csiro.au> writes:
> If you would like a 10 second R puzzle, you might like to think about
> this one:
> 
> 
> > g <- expand.grid(long = 130:140, lat = -(10:25))
> > gp <- transform(g, x = long, y = lat)
> Error in transform(g, x = long, y = lat) : 
>         object "long" not found
> 
> 
> I don't expect this hasn't come up before, but I can't find
mention of
> it.  I suggest that to minimise this little stumbling block for
> beginners (and others) we either
> 
> 	change the name of the principal argument in transform from 'x'
> to, say '.x' (or even 'data' as it is in 'with' for
example)  OR
> 
> 	at least put a note in the help file for 'transform' in the
> 'Detalis' section to say
>      
> 	*** NOTE: The only tag name unavailable to be used is 'x'. ***
Yes it has come up before (surprisingly rarely though), and you're
probably right although changing argument names of functions should
never be taken lightly as there could be people using the current
ones. 
> 
> Just another little seed.
...which is connected to my grievances with attach() &c the other day.
Something about transform() just isn't The Right Way.

-- 
   O__  ---- Peter Dalgaard             ?ster Farimagsgade 5, Entr.B
  c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
 (*) \(*) -- University of Copenhagen   Denmark          Ph:  (+45) 35327918
~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)                  FAX: (+45) 35327907

Hi John,

Unfortunately I don't think that will fix it because of partial matching.

(That would be OK if the argument sequence were reversed to:

	function(..., x.)

since partial matching does not occur with arguments coming after ..., but it
would break ALL existing code.)

Bill.

-----Original Message-----
From: John Fox [mailto:jfox at mcmaster.ca] 
Sent: Sunday, 12 February 2006 1:39 AM
To: 'Peter Dalgaard'; Venables, Bill (CMIS, Cleveland)
Cc: r-devel at stat.math.ethz.ch
Subject: RE: [Rd] Arguments of 'transform'


Dear Peter and Bill,

How about changing the current "x argument to something like
"x."? That
should make the problem that Bill points out less likely and still be
backwards compatible with using "x" in the call to transform().

Regards,
 John

--------------------------------
John Fox
Department of Sociology
McMaster University
Hamilton, Ontario
Canada L8S 4M4
905-525-9140x23604
http://socserv.mcmaster.ca/jfox 
-------------------------------- 
> -----Original Message-----
> From: r-devel-bounces at r-project.org 
> [mailto:r-devel-bounces at r-project.org] On Behalf Of Peter Dalgaard
> Sent: Saturday, February 11, 2006 4:43 AM
> To: Bill.Venables at csiro.au
> Cc: r-devel at stat.math.ethz.ch; p.dalgaard at biostat.ku.dk
> Subject: Re: [Rd] Arguments of 'transform'
> 
> <Bill.Venables at csiro.au> writes:
> 
> > If you would like a 10 second R puzzle, you might like to 
> think about 
> > this one:
> > 
> > 
> > > g <- expand.grid(long = 130:140, lat = -(10:25)) gp <- 
> transform(g, 
> > > x = long, y = lat)
> > Error in transform(g, x = long, y = lat) : 
> >         object "long" not found
> > 
> > 
> > I don't expect this hasn't come up before, but I can't
find
> mention of 
> > it.  I suggest that to minimise this little stumbling block for 
> > beginners (and others) we either
> > 
> > 	change the name of the principal argument in transform from
'x'
> > to, say '.x' (or even 'data' as it is in
'with' for example)  OR
> > 
> > 	at least put a note in the help file for 'transform' in 
> the 'Detalis' 
> > section to say
> >      
> > 	*** NOTE: The only tag name unavailable to be used is 'x'.
***
> 
> Yes it has come up before (surprisingly rarely though), and 
> you're probably right although changing argument names of 
> functions should never be taken lightly as there could be 
> people using the current ones. 
> 
> > 
> > Just another little seed.
> 
> ...which is connected to my grievances with attach() &c the other day.
> Something about transform() just isn't The Right Way.
> 
> -- 
>    O__  ---- Peter Dalgaard             ?ster Farimagsgade 5, Entr.B
>   c/ /'_ --- Dept. of Biostatistics     PO Box 2099, 1014 Cph. K
>  (*) \(*) -- University of Copenhagen   Denmark          Ph:  
> (+45) 35327918
> ~~~~~~~~~~ - (p.dalgaard at biostat.ku.dk)                  FAX: 
> (+45) 35327907
> 
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