[Rd] heads and tails

(Ted Harding) Ted.Harding at nessie.mcc.ac.uk
Sun May 1 09:07:37 CEST 2005

On 01-May-05 Bill.Venables at csiro.au wrote:
> Using head and tail recently, it occurred to me that it 
> would be very handy to have the unix convention more 
> fully, namely to allow negative values for "n" to 
> signify omission of lines rather than inclusion.
> Thus head(X, -1) would mean "all but the last line" and
>       tail(X, -1) would mean "all but the first line".
> Private correspondence has made me aware that this idea 
> is not new, and that there is no organised opposition to 
> it.  Moreover the code changes needed are trivial (and 
> I am happy to supply them if people want...) and no 
> presently working code would be broken.
> Has the time for this admittedly minor but harmless 
> convenience feature come at last?

I would agree that this seems desirable! As well as the
"trivial code changes needed", it also needs a probably
trivial switch of viewpoint from

  "n: size for the resulting object"


  "n: <whatever best encapsulates the above>"

Best wishes,

E-Mail: (Ted Harding) <Ted.Harding at nessie.mcc.ac.uk>
Fax-to-email: +44 (0)870 094 0861
Date: 01-May-05                                       Time: 07:57:58
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