All,
Martin: Thanks for this and all the other things you are doing to both
drive R forward and engage more with the community about things like this.
Apologies for missing this discussion the first time it came around and if
anything here has already been brought up, but I wonder what exactly you
mean when you want recycling behavior.
Specifically, based on an unrelated discussion with Henrik Bengtsson on
Twitter, I wonder if preserving the recycling behavior test is longer than
yes, no, but making the case where
length( test ) < max(length( yes ), length( no ))
would simplify usage for userRs in a useful way. I suspect it's easy to
forget that the result is not guaranteed to be the length of test, even
for intermediate and advanced users familiar with ifelse and it's
strengths/weaknesses.
I certainly agree (for what that's worth...) that
x = rnorm(100)
y = ifelse2(x > 0, 1L, 2L)
should continue to work.
Also, If we combine a stricter contract that the output will always be of
length with the suggestion of a specified output class the pseudo code
could be
ifelse2 = function(test, yes, no, outclass) {
lenout = length(test)
out = as( rep(yes, length.out = lenout), outclass)
out[!test] = as(rep(no, length.out = lenout)[!test], outclass)
#handle NA stuff
out
}
NAs could be tricky if outclass were allowed to be completely general, but
doable, I think? Another approach if we ARE fast-passing while leaving
ifelse intact is that maybe NA's in test just aren't allowed in ifelse2.
I'm not saying we should definitely do that, but it's possible and would
make things faster.
Finally, In terms of efficiency, with the stuff that Luke and I are working
on, the NA detection could be virtually free in certain cases, which could
give a nice boost for long vectors that don't have any NAs (and
'know'
that they don't).
Best,
~G
On Tue, Nov 15, 2016 at 3:58 AM, Martin Maechler <maechler at
stat.math.ethz.ch> wrote:
> Finally getting back to this :
>
> >>>>> Hadley Wickham <h.wickham at gmail.com>
> >>>>> on Mon, 15 Aug 2016 07:51:35 -0500 writes:
>
> > On Fri, Aug 12, 2016 at 11:31 AM, Hadley Wickham
> > <h.wickham at gmail.com> wrote:
> >>> >> One possibility would also be to consider a
> >>> "numbers-only" or >> rather "same
type"-only {e.g.,
> >>> would also work for characters} >> version.
> >>>
> >>> > I don't know what you mean by these.
> >>>
> >>> In the mean time, Bob Rudis mentioned dplyr::if_else(),
> >>> which is very relevant, thank you Bob!
> >>>
> >>> As I have found, that actually works in such a "same
> >>> type"-only way: It does not try to coerce, but gives
an
> >>> error when the classes differ, even in this somewhat
> >>> debatable case :
> >>>
> >>> > dplyr::if_else(c(TRUE, FALSE), 2:3, 0+10:11) Error:
> >>> `false` has type 'double' not 'integer'
> >>> >
> >>>
> >>> As documented, if_else() is clearly stricter than
> >>> ifelse() and e.g., also does no recycling (but of
> >>> length() 1).
> >>
> >> I agree that if_else() is currently too strict - it's
> >> particularly annoying if you want to replace some values
> >> with a missing:
> >>
> >> x <- sample(10) if_else(x > 5, NA, x) # Error: `false`
> >> has type 'integer' not 'logical'
> >>
> >> But I would like to make sure that this remains an error:
> >>
> >> if_else(x > 5, x, "BLAH")
> >>
> >> Because that seems more likely to be a user error (but
> >> reasonable people might certainly believe that it should
> >> just work)
> >>
> >> dplyr is more accommodating in other places (i.e. in
> >> bind_rows(), collapse() and the joins) but it's
> >> surprisingly hard to get all the details right. For
> >> example, what should the result of this call be?
> >>
> >> if_else(c(TRUE, FALSE), factor(c("a",
"b")),
> >> factor(c("c", "b"))
> >>
> >> Strictly speaking I think you could argue it's an error,
> >> but that's not very user-friendly. Should it be a factor
> >> with the union of the levels? Should it be a character
> >> vector + warning? Should the behaviour change if one set
> >> of levels is a subset of the other set?
> >>
> >> There are similar issues for POSIXct (if the time zones
> >> are different, which should win?), and difftimes
> >> (similarly for units). Ideally you'd like the behaviour
> >> to be extensible for new S3 classes, which suggests it
> >> should be a generic (and for the most general case, it
> >> would need to dispatch on both arguments).
>
> > One possible principle would be to use c() -
> > i.e. construct out as
>
> > out <- c(yes[0], no[0]
> > length(out) <- max(length(yes), length(no))
>
> yes; this would require that a `length<-` method works for the
> class of the result.
>
> Duncan Murdoch mentioned a version of this, in his very
> first reply:
>
> ans <- c(yes, no)[seq_along(test)]
> ans <- ans[seq_along(test)]
>
> which is less efficient for atomic vectors, but requires
> less from the class: it "only" needs `c` and `[` to work
>
> and a mixture of your two proposals would be possible too:
>
> ans <- c(yes[0], no[0])
> ans <- ans[seq_along(test)]
>
> which does *not* work for my "mpfr" numbers (CRAN package
'Rmpfr'),
> but that's a buglet in the c.mpfr() implementation of my Rmpfr
> package... (which has already been fixed in the development version on
> R-forge,
> https://r-forge.r-project.org/R/?group_id=386)
>
> > But of course that wouldn't help with factor responses.
>
> Yes. However, a version of Duncan's suggestion -- of treating
'yes' first
> -- does help in that case.
>
> For once, mainly as "feasability experiment",
> I have created a github gist to make my current ifelse2() proposal
> available
> for commenting, cloning, pullrequesting, etc:
>
> Consisting of 2 files
> - ifelse-def.R : Functions definitions only, basically all the current
> proposals, called ifelse*()
> - ifelse-checks.R : A simplistic checking function
> and examples calling it, notably demonstrating that my
> ifelse2() does work with
> "Date", <dateTime> (i.e. "POSIXct" and
"POSIXlt"), factors,
> and "mpfr" (the arbitrary-precision numbers in my package
"Rmpfr")
>
> Also if you are not on github, you can quickly get to the ifelse2()
> definition :
>
> https://gist.github.com/mmaechler/9cfc3219c4b89649313bfe6853d878
> 94#file-ifelse-def-r-L168
>
> > Also, if you're considering an improved ifelse(), I'd
> > strongly urge you to consider adding an `na` argument,
>
> I now did (called it 'NA.').
>
> > so that you can use ifelse() to transform all three
> > possible values in a logical vector.
>
> > Hadley
> > -- http://hadley.nz
>
> For those who really hate GH (and don't want or cannot easily follow
the
> above URL), here's my current definition:
>
>
> ##' Martin Maechler, 14. Nov 2016 --- taking into account Duncan M. and
> Hadley's
> ##' ideas in the R-devel thread starting at (my mom's 86th
birthday):
> ##' https://stat.ethz.ch/pipermail/r-devel/2016-August/072970.html
> ifelse2 <- function (test, yes, no, NA. = NA) {
> if(!is.logical(test)) {
> if(is.atomic(test))
> storage.mode(test) <- "logical"
> else ## typically a "class"; storage.mode<-()
typically fails
> test <- if(isS4(test)) methods::as(test,
"logical") else
> as.logical(test)
> }
>
> ## No longer optimize the "if (a) x else y" cases:
> ## Only "non-good" R users use ifelse(.) instead of if(.) in
these
> cases.
>
> ans <-
> tryCatch(rep(if(is.object(yes) && identical(class(yes),
class(no)))
> ## as c(o) or o[0] may not work for the class
> yes else c(yes[0], no[0]), length.out >
length(test)),
> error = function(e) { ## try asymmetric, yes-leaning
> r <- yes
> r[!test] <- no[!test]
> r
> })
> ok <- !(nas <- is.na(test))
> if (any(test[ok]))
> ans[test & ok] <- rep(yes, length.out = length(ans))[test
& ok]
> if (any(!test[ok]))
> ans[!test & ok] <- rep(no, length.out = length(ans))[!test
& ok]
> ans[nas] <- NA. # possibly coerced to class(ans)
> ans
> }
>
> ______________________________________________
> R-devel at r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>
--
Gabriel Becker, PhD
Associate Scientist (Bioinformatics)
Genentech Research
[[alternative HTML version deleted]]
Martin Maechler
2016-Nov-22 10:12 UTC
[Rd] ifelse() woes ... can we agree on a ifelse2() ?
>>>>> Gabriel Becker <gmbecker at ucdavis.edu> >>>>> on Tue, 15 Nov 2016 11:56:04 -0800 writes:> All, > Martin: Thanks for this and all the other things you are doing to both > drive R forward and engage more with the community about things like this. > Apologies for missing this discussion the first time it came around and if > anything here has already been brought up, but I wonder what exactly you > mean when you want recycling behavior. Thank you, Gabe. Note that my premise was really to get *away* from inheriting too much from 'test'. Hence, I have *not* been talking about replacing ifelse() but rather of providing a new ifelse2() [ or if_else() if Hadley was willing to ditch the dplyr one in favor of a base one] > Specifically, based on an unrelated discussion with Henrik Bengtsson on > Twitter, I wonder if preserving the recycling behavior test is longer than > yes, no, but making the case where > length( test ) < max(length( yes ), length( no )) > would simplify usage for userRs in a useful way. I'm sorry I don't understand the sentence above. > I suspect it's easy to > forget that the result is not guaranteed to be the length of test, even > for intermediate and advanced users familiar with ifelse and it's > strengths/weaknesses. > I certainly agree (for what that's worth...) that > x = rnorm(100) > y = ifelse2(x > 0, 1L, 2L) > should continue to work. (and give a a length 10 result). Also ifelse2(x > 0, sqrt(x), 0L) should work even though class(sqrt(x)) is "numeric" and the one of 0L is "integer", and I'd argue ifelse2(x < 0, sqrt(x + 0i), sqrt(x)) should also continue to work as with ifelse(). > Also, If we combine a stricter contract that the output will always be of > length with the suggestion of a specified output class that was not my intent here.... but would be another interesting extension. However, I would like to keep R-semantic silent coercions such as logical < integer < double < complex and your pseudo code below would not work so easily I think. > the pseudo code could be (I'm changing assignment '=' to '<-' ... [please!] ) > ifelse2 <- function(test, yes, no, outclass) { > lenout <- length(test) > out <- as( rep(yes, length.out <- lenout), outclass) > out[!test] <- as(rep(no, length.out = lenout)[!test], outclass) > # handle NA stuff > out > } > NAs could be tricky if outclass were allowed to be completely general, but > doable, I think? Another approach if we ARE fast-passing while leaving > ifelse intact is that maybe NA's in test just aren't allowed in ifelse2. > I'm not saying we should definitely do that, but it's possible and would > make things faster. > Finally, In terms of efficiency, with the stuff that Luke and I are working > on, the NA detection could be virtually free in certain cases, which could > give a nice boost for long vectors that don't have any NAs (and 'know' > that they don't). That *is* indeed a very promising prospect! Thank you in advance! > Best, > ~G I still am bit disappointed by the fact that it seems nobody has taken a good look at my ifelse2() proposal. I really would like an alternative to ifelse() in *addition* to the current ifelse(), but hopefully in the future being used in quite a few places instead of ifelse() efficiency but for changed semantics, namely working for considerably more "vector like" classes of 'yes' and 'no' than the current ifelse(). As I said, the current proposal works for objects of class "Date", "POSIXct", "POSIXlt", "factor", "mpfr" (pkg 'Rmpfr') and hopefully for "sparseVector" (in a next version of the 'Matrix' pkg). Martin > On Tue, Nov 15, 2016 at 3:58 AM, Martin Maechler <maechler at stat.math.ethz.ch >> wrote: >> Finally getting back to this : >> >> >>>>> Hadley Wickham <h.wickham at gmail.com> >> >>>>> on Mon, 15 Aug 2016 07:51:35 -0500 writes: >> >> > On Fri, Aug 12, 2016 at 11:31 AM, Hadley Wickham >> > <h.wickham at gmail.com> wrote: >> >>> >> One possibility would also be to consider a >> >>> "numbers-only" or >> rather "same type"-only {e.g., >> >>> would also work for characters} >> version. >> >>> >> >>> > I don't know what you mean by these. >> >>> >> >>> In the mean time, Bob Rudis mentioned dplyr::if_else(), >> >>> which is very relevant, thank you Bob! >> >>> >> >>> As I have found, that actually works in such a "same >> >>> type"-only way: It does not try to coerce, but gives an >> >>> error when the classes differ, even in this somewhat >> >>> debatable case : >> >>> >> >>> > dplyr::if_else(c(TRUE, FALSE), 2:3, 0+10:11) Error: >> >>> `false` has type 'double' not 'integer' >> >>> > >> >>> >> >>> As documented, if_else() is clearly stricter than >> >>> ifelse() and e.g., also does no recycling (but of >> >>> length() 1). >> >> >> >> I agree that if_else() is currently too strict - it's >> >> particularly annoying if you want to replace some values >> >> with a missing: >> >> >> >> x <- sample(10) if_else(x > 5, NA, x) # Error: `false` >> >> has type 'integer' not 'logical' >> >> >> >> But I would like to make sure that this remains an error: >> >> >> >> if_else(x > 5, x, "BLAH") >> >> >> >> Because that seems more likely to be a user error (but >> >> reasonable people might certainly believe that it should >> >> just work) >> >> >> >> dplyr is more accommodating in other places (i.e. in >> >> bind_rows(), collapse() and the joins) but it's >> >> surprisingly hard to get all the details right. For >> >> example, what should the result of this call be? >> >> >> >> if_else(c(TRUE, FALSE), factor(c("a", "b")), >> >> factor(c("c", "b")) >> >> >> >> Strictly speaking I think you could argue it's an error, >> >> but that's not very user-friendly. Should it be a factor >> >> with the union of the levels? Should it be a character >> >> vector + warning? Should the behaviour change if one set >> >> of levels is a subset of the other set? >> >> >> >> There are similar issues for POSIXct (if the time zones >> >> are different, which should win?), and difftimes >> >> (similarly for units). Ideally you'd like the behaviour >> >> to be extensible for new S3 classes, which suggests it >> >> should be a generic (and for the most general case, it >> >> would need to dispatch on both arguments). >> >> > One possible principle would be to use c() - >> > i.e. construct out as >> >> > out <- c(yes[0], no[0] >> > length(out) <- max(length(yes), length(no)) >> >> yes; this would require that a `length<-` method works for the >> class of the result. >> >> Duncan Murdoch mentioned a version of this, in his very >> first reply: >> >> ans <- c(yes, no)[seq_along(test)] >> ans <- ans[seq_along(test)] >> >> which is less efficient for atomic vectors, but requires >> less from the class: it "only" needs `c` and `[` to work >> >> and a mixture of your two proposals would be possible too: >> >> ans <- c(yes[0], no[0]) >> ans <- ans[seq_along(test)] >> >> which does *not* work for my "mpfr" numbers (CRAN package 'Rmpfr'), >> but that's a buglet in the c.mpfr() implementation of my Rmpfr >> package... (which has already been fixed in the development version on >> R-forge, >> https://r-forge.r-project.org/R/?group_id=386) >> >> > But of course that wouldn't help with factor responses. >> >> Yes. However, a version of Duncan's suggestion -- of treating 'yes' first >> -- does help in that case. >> >> For once, mainly as "feasability experiment", >> I have created a github gist to make my current ifelse2() proposal >> available >> for commenting, cloning, pullrequesting, etc: >> >> Consisting of 2 files >> - ifelse-def.R : Functions definitions only, basically all the current >> proposals, called ifelse*() >> - ifelse-checks.R : A simplistic checking function >> and examples calling it, notably demonstrating that my >> ifelse2() does work with >> "Date", <dateTime> (i.e. "POSIXct" and "POSIXlt"), factors, >> and "mpfr" (the arbitrary-precision numbers in my package "Rmpfr") >> >> Also if you are not on github, you can quickly get to the ifelse2() >> definition : >> >> https://gist.github.com/mmaechler/9cfc3219c4b89649313bfe6853d878 >> 94#file-ifelse-def-r-L168 >> >> > Also, if you're considering an improved ifelse(), I'd >> > strongly urge you to consider adding an `na` argument, >> >> I now did (called it 'NA.'). >> >> > so that you can use ifelse() to transform all three >> > possible values in a logical vector. >> >> > Hadley >> > -- http://hadley.nz >> >> For those who really hate GH (and don't want or cannot easily follow the >> above URL), here's my current definition: >> >> >> ##' Martin Maechler, 14. Nov 2016 --- taking into account Duncan M. and >> Hadley's >> ##' ideas in the R-devel thread starting at (my mom's 86th birthday): >> ##' https://stat.ethz.ch/pipermail/r-devel/2016-August/072970.html >> ifelse2 <- function (test, yes, no, NA. = NA) { >> if(!is.logical(test)) { >> if(is.atomic(test)) >> storage.mode(test) <- "logical" >> else ## typically a "class"; storage.mode<-() typically fails >> test <- if(isS4(test)) methods::as(test, "logical") else >> as.logical(test) >> } >> >> ## No longer optimize the "if (a) x else y" cases: >> ## Only "non-good" R users use ifelse(.) instead of if(.) in these >> cases. >> >> ans <- >> tryCatch(rep(if(is.object(yes) && identical(class(yes), class(no))) >> ## as c(o) or o[0] may not work for the class >> yes else c(yes[0], no[0]), length.out >> length(test)), >> error = function(e) { ## try asymmetric, yes-leaning >> r <- yes >> r[!test] <- no[!test] >> r >> }) >> ok <- !(nas <- is.na(test)) >> if (any(test[ok])) >> ans[test & ok] <- rep(yes, length.out = length(ans))[test & ok] >> if (any(!test[ok])) >> ans[!test & ok] <- rep(no, length.out = length(ans))[!test & ok] >> ans[nas] <- NA. # possibly coerced to class(ans) >> ans >> } >> >> ______________________________________________ >> R-devel at r-project.org mailing list >> https://stat.ethz.ch/mailman/listinfo/r-devel >> > -- > Gabriel Becker, PhD > Associate Scientist (Bioinformatics) > Genentech Research > [[alternative HTML version deleted]]
Martin et al., On Tue, Nov 22, 2016 at 2:12 AM, Martin Maechler <maechler at stat.math.ethz.ch> wrote:> > Note that my premise was really to get *away* from inheriting > too much from 'test'. > Hence, I have *not* been talking about replacing ifelse() but > rather of providing a new ifelse2() > > [ or if_else() if Hadley was willing to ditch the dplyr one > in favor of a base one] > > > Specifically, based on an unrelated discussion with Henrik Bengtsson > on > > Twitter, I wonder if preserving the recycling behavior test is > longer than > > yes, no, but making the case where > > > length( test ) < max(length( yes ), length( no )) > > > would simplify usage for userRs in a useful way. >That was a copyediting bug on my part, it seems I hit send with my message only half-edited/proofread. Apologies. That should have said that making the case where test is the one that will be recycled (because it is shorter than either yes or no) an error. My claim is that the fact that test itself can be recycled, rather than just yes or no, is confusing to many R users. If we are writing an ifelse2 we might want to drop that feature and just throw an error in that case. (Users could still use the original ifelse if they understand and specifically want that behavior). Does that make more sense?> > > Also, If we combine a stricter contract that the output will always > be of > > length with the suggestion of a specified output class > >Here, again, I was talking about the restriction that the output be guaranteed to be the length of test, regardless of the length of yes and no. That, combined with a specific, guaranteed output class would make a much narrower/more restricted but also (I argue) much easier to understand function. Particularly for beginning and intermediate users. I do hear what you're saying about silent conversion, though, so what I'm describing might be a third function (ifelse3 for lack of a better name for now), as you pointed out.> that was not my intent here.... but would be another interesting > extension. However, I would like to keep R-semantic silent coercions > such as > logical < integer < double < complex > > and your pseudo code below would not work so easily I think. > > > the pseudo code could be > > (I'm changing assignment '=' to '<-' ... [please!] ) > > > ifelse2 <- function(test, yes, no, outclass) { > > lenout <- length(test) > > out <- as( rep(yes, length.out <- lenout), outclass) > > out[!test] <- as(rep(no, length.out = lenout)[!test], outclass) > > # handle NA stuff > > out > > } > > > > NAs could be tricky if outclass were allowed to be completely > general, but > > doable, I think? Another approach if we ARE fast-passing while > leaving > > ifelse intact is that maybe NA's in test just aren't allowed in > ifelse2. > > I'm not saying we should definitely do that, but it's possible and > would > > make things faster. > > > Finally, In terms of efficiency, with the stuff that Luke and I are > working > > on, the NA detection could be virtually free in certain cases, which > could > > give a nice boost for long vectors that don't have any NAs (and > 'know' > > that they don't). > > That *is* indeed a very promising prospect! > Thank you in advance! > > > Best, > > ~G > > I still am bit disappointed by the fact that it seems nobody has > taken a good look at my ifelse2() proposal. >I plan to look at it soon. Thanks again for all your work. ~G> > I really would like an alternative to ifelse() in *addition* to > the current ifelse(), but hopefully in the future being used in > quite a few places instead of ifelse() > efficiency but for changed semantics, namely working for considerably > more "vector like" classes of 'yes' and 'no' than the current > ifelse(). > > As I said, the current proposal works for objects of class > "Date", "POSIXct", "POSIXlt", "factor", "mpfr" (pkg 'Rmpfr') > and hopefully for "sparseVector" (in a next version of the 'Matrix' pkg). > > Martin > > > On Tue, Nov 15, 2016 at 3:58 AM, Martin Maechler < > maechler at stat.math.ethz.ch > >> wrote: > > >> Finally getting back to this : > >> > >> >>>>> Hadley Wickham <h.wickham at gmail.com> > >> >>>>> on Mon, 15 Aug 2016 07:51:35 -0500 writes: > >> > >> > On Fri, Aug 12, 2016 at 11:31 AM, Hadley Wickham > >> > <h.wickham at gmail.com> wrote: > >> >>> >> One possibility would also be to consider a > >> >>> "numbers-only" or >> rather "same type"-only {e.g., > >> >>> would also work for characters} >> version. > >> >>> > >> >>> > I don't know what you mean by these. > >> >>> > >> >>> In the mean time, Bob Rudis mentioned dplyr::if_else(), > >> >>> which is very relevant, thank you Bob! > >> >>> > >> >>> As I have found, that actually works in such a "same > >> >>> type"-only way: It does not try to coerce, but gives an > >> >>> error when the classes differ, even in this somewhat > >> >>> debatable case : > >> >>> > >> >>> > dplyr::if_else(c(TRUE, FALSE), 2:3, 0+10:11) Error: > >> >>> `false` has type 'double' not 'integer' > >> >>> > > >> >>> > >> >>> As documented, if_else() is clearly stricter than > >> >>> ifelse() and e.g., also does no recycling (but of > >> >>> length() 1). > >> >> > >> >> I agree that if_else() is currently too strict - it's > >> >> particularly annoying if you want to replace some values > >> >> with a missing: > >> >> > >> >> x <- sample(10) if_else(x > 5, NA, x) # Error: `false` > >> >> has type 'integer' not 'logical' > >> >> > >> >> But I would like to make sure that this remains an error: > >> >> > >> >> if_else(x > 5, x, "BLAH") > >> >> > >> >> Because that seems more likely to be a user error (but > >> >> reasonable people might certainly believe that it should > >> >> just work) > >> >> > >> >> dplyr is more accommodating in other places (i.e. in > >> >> bind_rows(), collapse() and the joins) but it's > >> >> surprisingly hard to get all the details right. For > >> >> example, what should the result of this call be? > >> >> > >> >> if_else(c(TRUE, FALSE), factor(c("a", "b")), > >> >> factor(c("c", "b")) > >> >> > >> >> Strictly speaking I think you could argue it's an error, > >> >> but that's not very user-friendly. Should it be a factor > >> >> with the union of the levels? Should it be a character > >> >> vector + warning? Should the behaviour change if one set > >> >> of levels is a subset of the other set? > >> >> > >> >> There are similar issues for POSIXct (if the time zones > >> >> are different, which should win?), and difftimes > >> >> (similarly for units). Ideally you'd like the behaviour > >> >> to be extensible for new S3 classes, which suggests it > >> >> should be a generic (and for the most general case, it > >> >> would need to dispatch on both arguments). > >> > >> > One possible principle would be to use c() - > >> > i.e. construct out as > >> > >> > out <- c(yes[0], no[0] > >> > length(out) <- max(length(yes), length(no)) > >> > >> yes; this would require that a `length<-` method works for the > >> class of the result. > >> > >> Duncan Murdoch mentioned a version of this, in his very > >> first reply: > >> > >> ans <- c(yes, no)[seq_along(test)] > >> ans <- ans[seq_along(test)] > >> > >> which is less efficient for atomic vectors, but requires > >> less from the class: it "only" needs `c` and `[` to work > >> > >> and a mixture of your two proposals would be possible too: > >> > >> ans <- c(yes[0], no[0]) > >> ans <- ans[seq_along(test)] > >> > >> which does *not* work for my "mpfr" numbers (CRAN package 'Rmpfr'), > >> but that's a buglet in the c.mpfr() implementation of my Rmpfr > >> package... (which has already been fixed in the development version > on > >> R-forge, > >> https://r-forge.r-project.org/R/?group_id=386) > >> > >> > But of course that wouldn't help with factor responses. > >> > >> Yes. However, a version of Duncan's suggestion -- of treating > 'yes' first > >> -- does help in that case. > >> > >> For once, mainly as "feasability experiment", > >> I have created a github gist to make my current ifelse2() proposal > >> available > >> for commenting, cloning, pullrequesting, etc: > >> > >> Consisting of 2 files > >> - ifelse-def.R : Functions definitions only, basically all the > current > >> proposals, called ifelse*() > >> - ifelse-checks.R : A simplistic checking function > >> and examples calling it, notably demonstrating that my > >> ifelse2() does work with > >> "Date", <dateTime> (i.e. "POSIXct" and "POSIXlt"), factors, > >> and "mpfr" (the arbitrary-precision numbers in my package "Rmpfr") > >> > >> Also if you are not on github, you can quickly get to the ifelse2() > >> definition : > >> > >> https://gist.github.com/mmaechler/9cfc3219c4b89649313bfe6853d878 > >> 94#file-ifelse-def-r-L168 > >> > >> > Also, if you're considering an improved ifelse(), I'd > >> > strongly urge you to consider adding an `na` argument, > >> > >> I now did (called it 'NA.'). > >> > >> > so that you can use ifelse() to transform all three > >> > possible values in a logical vector. > >> > >> > Hadley > >> > -- http://hadley.nz > >> > >> For those who really hate GH (and don't want or cannot easily > follow the > >> above URL), here's my current definition: > >> > >> > >> ##' Martin Maechler, 14. Nov 2016 --- taking into account Duncan M. > and > >> Hadley's > >> ##' ideas in the R-devel thread starting at (my mom's 86th > birthday): > >> ##' https://stat.ethz.ch/pipermail/r-devel/2016-August/072970.html > >> ifelse2 <- function (test, yes, no, NA. = NA) { > >> if(!is.logical(test)) { > >> if(is.atomic(test)) > >> storage.mode(test) <- "logical" > >> else ## typically a "class"; storage.mode<-() typically fails > >> test <- if(isS4(test)) methods::as(test, "logical") else > >> as.logical(test) > >> } > >> > >> ## No longer optimize the "if (a) x else y" cases: > >> ## Only "non-good" R users use ifelse(.) instead of if(.) in these > >> cases. > >> > >> ans <- > >> tryCatch(rep(if(is.object(yes) && identical(class(yes), class(no))) > >> ## as c(o) or o[0] may not work for the class > >> yes else c(yes[0], no[0]), length.out > >> length(test)), > >> error = function(e) { ## try asymmetric, yes-leaning > >> r <- yes > >> r[!test] <- no[!test] > >> r > >> }) > >> ok <- !(nas <- is.na(test)) > >> if (any(test[ok])) > >> ans[test & ok] <- rep(yes, length.out = length(ans))[test & ok] > >> if (any(!test[ok])) > >> ans[!test & ok] <- rep(no, length.out = length(ans))[!test & ok] > >> ans[nas] <- NA. # possibly coerced to class(ans) > >> ans > >> } > >> > >> ______________________________________________ > >> R-devel at r-project.org mailing list > >> https://stat.ethz.ch/mailman/listinfo/r-devel > >> > > > > > -- > > Gabriel Becker, PhD > > Associate Scientist (Bioinformatics) > > Genentech Research > > > [[alternative HTML version deleted]] > >-- Gabriel Becker, PhD Associate Scientist (Bioinformatics) Genentech Research [[alternative HTML version deleted]]