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
