On 12/31/2005 12:57 PM, Gabor Grothendieck wrote: > It does not achieve design consistency.
It's consistent with the way it has been for at least 7 years, and is consistent with xyz.coords(). One would have to > specify NULL but that should not really be necessary. In fact, one almost never needs to specify NULL there. It's the default value for y in the high level functions that call xy.coords, so it is put there automatically. Duncan Murdoch > > On 12/31/05, Duncan Murdoch <[EMAIL PROTECTED]> wrote: > >>On 12/31/2005 12:21 PM, Gabor Grothendieck wrote: >> >>>I think the point is that (1) it does not work as documented and (2) in >>>most functions one can omit unnecessary args without having >>>to specify NULL so its behvaior seems inconsistent from a design >>>viewpoint. By allowing either missing or NULL it will work as documented, >>>and probably intended, yet continue to be backward compatible with >>>existing usages. >> >>But a simpler change is to change the documentation, and it achieves all >>of those objectives. >> >>Duncan Murdoch >> >>>On 12/31/05, Duncan Murdoch <[EMAIL PROTECTED]> wrote: >>> >>> >>>>On 12/31/2005 8:57 AM, Gabor Grothendieck wrote: >>>> >>>> >>>>>It could be changed to missing(y) || is.null(y) and the docs amended. >>>>>That way existing code will continue to work and code that otherwise >>>>>gives an error currently, but should have worked, will now work too. >>>> >>>>Can you give an example where you would want to use xy.coords(y ~ x)? >>>>Normally xy.coords() is used in other functions, and they can default y >>>>to NULL (see plot.default, for example). >>>> >>>>Duncan Murdoch >>>> >>>> >>>>>On 12/31/05, Duncan Murdoch <[EMAIL PROTECTED]> wrote: >>>>> >>>>> >>>>> >>>>>>On 12/30/2005 10:10 PM, Gabor Grothendieck wrote: >>>>>> >>>>>> >>>>>> >>>>>>>In ?xy.coords it says: >>>>>>> >>>>>>> If 'y' is missing and 'x' is a >>>>>>> >>>>>>> formula: of the form 'yvar ~ xvar'. 'xvar' and 'yvar' are used as >>>>>>> x and y variables. >>>>>>> >>>>>>> list: containing components 'x' and 'y', these are used to define >>>>>>> plotting coordinates. >>>>>>> >>>>>>> time series: the x values are taken to be 'time(x)' and the y >>>>>>> values to be the time series. >>>>>>> >>>>>>> matrix with two columns: the first is assumed to contain the x >>>>>>> values and the second the y values. >>>>>>> >>>>>>>however, in fact, if y is missing an error is given. e.g. >>>>>>> >>>>>>>x <- 1:3 >>>>>>>y <- 4:6 >>>>>>>xy.coords(y ~ x) # error >>>>>>>xy.coords(cbind(x, y)) # error >>>>>>>xy.coords(ts(y)) # error >>>>>>> >>>>>>>Looking at the code, is.null(y) in the first line of the >>>>>>>body should be missing(y) . >>>>>> >>>>>>It would be better to change the docs to say "if 'y' is NULL ...". The >>>>>>code has been the way it is for years and years, and is widely used. >>>>>> >>>>>>Changing the test to missing(y) would mean all existing uses that put a >>>>>>NULL there would need to be changed. >>>>>> >>>>>>Adding a default value of NULL to y would have less impact, but I'd >>>>>>still be worried about it having long-range bad effects. >>>>>> >>>>>>Duncan Murdoch >>>>>> >>>> >>>> >> > > ______________________________________________ > R-devel@r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
