>>>>> William Dunlap via R-help <r-help@r-project.org>
>>>>> on Wed, 23 Mar 2016 13:56:35 -0700 writes:
> I don't know what is in R's poly(), but if it is like S+'s or TERR's then
> one could do
> if (anyNA(x)) {
> nax <- na.exclude(x)
> px <- poly(x = nax, degree = degree, coefs = coefs, raw =
> raw, simple = simple)
> px <- structure(naresid(attr(nax, "na.action"), px), coefs
> = attr(px, "coefs"), degree = attr(px, "degree"), class = attr(px,
"class"))
> return(px)
> }
> and get nice results in the usual raw=FALSE case as well. Similar stuff
> could be done in the multivariate cases.
I don't have too much time for that now,
and I know that Bill Dunlap cannot provide patches for R --- for
good reasons, though it's a pity for us! ---
but you can, Liviu!
So, and as you see at every startup of R :
"R is a collaborative project with many contributors."
I'm willing to try "good-looking" patches.
(to the *sources*, *NOT* to a printout of the function in your R console!)
Martin Maechler
ETH Zurich and R Core Team.
> Bill Dunlap
> TIBCO Software
> wdunlap tibco.com
> On Wed, Mar 23, 2016 at 1:41 PM, Liviu Andronic <landronim...@gmail.com>
> wrote:
>> On Wed, Mar 23, 2016 at 9:29 PM, William Dunlap <wdun...@tibco.com>
wrote:
>> > I think the worst aspect of this restriction in poly() is that when
>> > you use poly in the formula of a model-fitting function you cannot
>> > have any missing values in the data, even if you supply
>> > na.action=na.exclude.
>> >
>> > > d <- transform(data.frame(y=c(-1,1:10)), x=log(y))
>> > Warning message:
>> > In log(y) : NaNs produced
>> > > fit <- lm(y ~ poly(x, 3), data=d, na.action=na.exclude)
>> > Error in poly(x, 3) : missing values are not allowed in 'poly'
>> >
>> > Thus people are pushed to using a less stable formulation like
>> > > fit <- lm(y ~ x + I(x^2) + I(x^3), data=d, na.action=na.exclude)
>> >
>> My difficulty precisely. What's more, I inspected the code for `poly`
>> and at least for the simple case of raw=TRUE it seems trivial to
>> support NAs. It suffices to change line 15 of the function:
>> if (anyNA(x)) stop("missing values are not allowed in 'poly'")
>>
>> to:
>> if (!raw && anyNA(x)) stop("missing values are not allowed in 'poly'")
>>
>> This way for raw polynomials estimation continues unimpeded. With the
>> change above, I get this:
>> > poly(x, degree = 2, raw=TRUE)
>> 1 2
>> [1,] NA NA
>> [2,] 1 1
>> [3,] 2 4
>> [4,] 3 9
>> [5,] 4 16
>> [6,] 5 25
>> [7,] 6 36
>> [8,] 7 49
>> [9,] 8 64
>> [10,] 9 81
>> [11,] 10 100
>> attr(,"degree")
>> [1] 1 2
>> attr(,"class")
>> [1] "poly" "matrix"
>>
>>
>> Regards,
>> Liviu
>>
>>
>> >
>> > Bill Dunlap
>> > TIBCO Software
>> > wdunlap tibco.com
>> >
>> > On Wed, Mar 23, 2016 at 12:59 PM, Liviu Andronic
<landronim...@gmail.com
>> >
>> > wrote:
>> >>
>> >> Dear all,
>> >> I'm a bit surprised by this behavior in poly:
>> >>
>> >> x <- c(NA, 1:10)
>> >> poly(x, degree = 2, raw=TRUE)
>> >> ## Error in poly(x, degree = 2, raw = TRUE) :
>> >> ## missing values are not allowed in 'poly'
>> >> x^2
>> >> ## [1] NA 1 4 9 16 25 36 49 64 81 100
>> >>
>> >> As you can see, poly() will fail if the vector contains NAs, whereas
>> >> it is perfectly possible to obtain the square of the vector manually.
>> >>
>> >> Is there a reason for this limitation in poly?
>> >>
>> >> Regards,
>> >> Liviu
>> >>
>> >>
>> >> --
>> >> Do you think you know what math is?
>> >> http://www.ideasroadshow.com/issues/ian-stewart-2013-08-02
>> >> Or what it means to be intelligent?
>> >> http://www.ideasroadshow.com/issues/john-duncan-2013-08-30
>> >> Think again:
>> >> http://www.ideasroadshow.com/library
>> >>
>> >> ______________________________________________
>> >> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
>> >> https://stat.ethz.ch/mailman/listinfo/r-help
>> >> PLEASE do read the posting guide
>> >> http://www.R-project.org/posting-guide.html
>> >> and provide commented, minimal, self-contained, reproducible code.
>> >
>> >
>>
>>
>>
>> --
>> Do you think you know what math is?
>> http://www.ideasroadshow.com/issues/ian-stewart-2013-08-02
>> Or what it means to be intelligent?
>> http://www.ideasroadshow.com/issues/john-duncan-2013-08-30
>> Think again:
>> http://www.ideasroadshow.com/library
>>
> [[alternative HTML version deleted]]
> ______________________________________________
> R-help@r-project.org mailing list -- To UNSUBSCRIBE and more, see
> https://stat.ethz.ch/mailman/listinfo/r-help
> PLEASE do read the posting guide
http://www.R-project.org/posting-guide.html
> and provide commented, minimal, self-contained, reproducible code.
______________________________________________
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