On 12/31/2005 3:26 PM, Gabor Grothendieck wrote: > I think this is just playng with words.
I'm starting to be convinced of that by the fact that you haven't posted any sample code where using a single parameter would be desirable. The fact that its always been > like that is not sufficient and is not related to consistency. > xyz.coords also does not work in accordance with the help file > so the fact that the error extends to it just means they are both > in error. > > Modularity means loose coupling -- i.e. a function should be > as independent as possible from its surroundings. The fact > that the second argument is not missing in uses within R base > is not a valid argument for appropriate attention to this principle. > > Furthermore, its clear that the current way it works is not even > the intended way -- the intended and better way is as documented > and the software, not the documentation, ought to be changed. Take a look at the examples. It's pretty clear that it is working as intended, and the documentation incorrectly says "missing" where it means "NULL". Duncan Murdoch > > > On 12/31/05, Duncan Murdoch <[EMAIL PROTECTED]> wrote: > >>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 ______________________________________________ R-devel@r-project.org mailing list https://stat.ethz.ch/mailman/listinfo/r-devel
