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? Bill Venables, CMIS, CSIRO Laboratories, PO Box 120, Cleveland, Qld. 4163 AUSTRALIA Phone: +61 7 3826 7251 Fax: +61 7 3826 7304 Mobile: +61 4 1963 4642 Home: +61 7 3286 7700 mailto:Bill.Venables@csiro.au http://www.cmis.csiro.au/bill.venables/
On 01-May-05 Bill.Venables@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" to "n: <whatever best encapsulates the above>" Best wishes, Ted. -------------------------------------------------------------------- E-Mail: (Ted Harding) <Ted.Harding@nessie.mcc.ac.uk> Fax-to-email: +44 (0)870 094 0861 Date: 01-May-05 Time: 07:57:58 ------------------------------ XFMail ------------------------------