Re: [Rd] quantile() type 1 for some ordered factors in R-devel

[Trang Le]

Hi Tobias,

I believe this is due to the implementation of the new method for c():
c.factor() on May 11, 2020. I have very recently experienced issues around
this addition as well.

For this particular instance, the following line of code in
quantile.default() no longer gives "integer" but instead yields "factor".

x <- c(x[1L], x[1L], x, x[n], x[n])

Hence, the following calculation qs results in named factor instead of
integer, which is not expected as input in the final

qs <- factor(qs, levels = seq_along(lx), labels = lx, ordered = TRUE)

Personally, I'm a bit surprised that this change is being made on a minor
release.

Best,
Trang Le

On Mon, May 18, 2020 at 12:36 PM Tobias Rockel  wrote:

> Hi,
>
> In R-devel (2020-05-17 r78478) quantile() type 1 seems to behave a little
> bit strange for some ordered factors:
> quantile(factor(1:3, ordered = TRUE), 0.5, type = 1)
> returns “2” as expected. But
> quantile(factor(2:4, ordered = TRUE), 0.5, type = 1)
> returns “4” and
> quantile(factor(3:5, ordered = TRUE), 0.5, type = 1)
> returns “NA”. Furthermore, the function returns “NA” for calls like
> quantile(factor(c("a", "b", "c"), ordered = TRUE), 0.5, type = 1)
>
> In R 4.0.0 everything seems fine (return values “2”, “3”, “4”, “b”). If the
> vectors are treated as numeric, everything seems to work fine in R-devel,
> too. For example
> quantile(3:5, 0.5, type = 1)
> returns “4” in R-devel and R 4.0.0.
>
> Best regards,
> Tobias Rockel
>
> [[alternative HTML version deleted]]
>
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Re: [Rd] quantile() type 1 for some ordered factors in R-devel

[Trang Le]

Hi Kurt,

Thank you for fixing quantile(). However, do you think c.factor() can
potentially break more functions? For example, with this new change,
classification from the partykit package using predict() comes back NA
because of this:

https://github.com/cran/partykit/blob/597245ef3dfc98411ce919b74c68ba565f077c47/R/party.R#L500

I understand that most of the fixes will probably be simple with
as.numeric() or as.integer(), but tracing down these breaks can be
time-consuming .
What about a warning whenever code that would trigger c.factor() is called?
This way users are given a chance to update packages and code.

Thanks,
Trang

On Wed, May 20, 2020 at 1:53 AM Kurt Hornik  wrote:

> > Tobias Rockel writes:
>
> Thanks for spotting this, and also to Hadley for reporting to me
> directly.
>
> Fixed now with c78501.
>
> Best
> -k
>
> > Hi,
> > In R-devel (2020-05-17 r78478) quantile() type 1 seems to behave a little
> > bit strange for some ordered factors:
> > quantile(factor(1:3, ordered = TRUE), 0.5, type = 1)
> > returns “2” as expected. But
> > quantile(factor(2:4, ordered = TRUE), 0.5, type = 1)
> > returns “4” and
> > quantile(factor(3:5, ordered = TRUE), 0.5, type = 1)
> > returns “NA”. Furthermore, the function returns “NA” for calls like
> > quantile(factor(c("a", "b", "c"), ordered = TRUE), 0.5, type = 1)
>
> > In R 4.0.0 everything seems fine (return values “2”, “3”, “4”, “b”). If
> the
> > vectors are treated as numeric, everything seems to work fine in R-devel,
> > too. For example
> > quantile(3:5, 0.5, type = 1)
> > returns “4” in R-devel and R 4.0.0.
>
> > Best regards,
> > Tobias Rockel
>
> >   [[alternative HTML version deleted]]
>
> > __
> > 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
>

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