Gabriel Becker
2016-Sep-08 17:22 UTC
[Rd] R (development) changes in arith, logic, relop with (0-extent) arrays
On Thu, Sep 8, 2016 at 10:05 AM, William Dunlap <wdunlap at tibco.com> wrote:> Shouldn't binary operators (arithmetic and logical) should throw an error > when one operand is NULL (or other type that doesn't make sense)? This is > a different case than a zero-length operand of a legitimate type. E.g., > any(x < 0) > should return FALSE if x is number-like and length(x)==0 but give an error > if x is NULL. >Bill, That is a good point. I can see the argument for this in the case that the non-zero length is 1. I'm not sure which is better though. If we switch any() to all(), things get murky. Mathematically, all(x<0) is TRUE if x is length 0 (as are all(x==0), and all(x>0)), but the likelihood of this being a thought-bug on the author's part is exceedingly high, imho. So the desirable behavior seems to depend on the angle we look at it from. My personal opinion is that x < y with length(x)==0 should fail if length(y)> 1, at least, and I'd be for it being an error even if y is length 1,though I do acknowledge this is more likely (though still quite unlikely imho) to be the intended behavior. ~G> > I.e., I think the type check should be done before the length check. > > > Bill Dunlap > TIBCO Software > wdunlap tibco.com > > On Thu, Sep 8, 2016 at 8:43 AM, Gabriel Becker <gmbecker at ucdavis.edu> > wrote: > >> Martin, >> >> Like Robin and Oliver I think this type of edge-case consistency is >> important and that it's fantastic that R-core - and you personally - are >> willing to tackle some of these "gotcha" behaviors. "Little" stuff like >> this really does combine to go a long way to making R better and better. >> >> I do wonder a bit about the >> >> x = 1:2 >> >> y = NULL >> >> x < y >> >> case. >> >> Returning a logical of length 0 is more backwards compatible, but is it >> ever what the author actually intended? I have trouble thinking of a case >> where that less-than didn't carry an implicit assumption that y was >> non-NULL. I can say that in my own code, I've never hit that behavior in >> a >> case that wasn't an error. >> >> My vote (unless someone else points out a compelling use for the behavior) >> is for the to throw an error. As a developer, I'd rather things like this >> break so the bug in my logic is visible, rather than propagating as the >> 0-length logical is &'ed or |'ed with other logical vectors, or used to >> subset, or (in the case it should be length 1) passed to if() (if throws >> an >> error now, but the rest would silently "work"). >> >> Best, >> ~G >> >> On Thu, Sep 8, 2016 at 3:49 AM, Martin Maechler < >> maechler at stat.math.ethz.ch> >> wrote: >> >> > >>>>> robin hankin <hankin.robin at gmail.com> >> > >>>>> on Thu, 8 Sep 2016 10:05:21 +1200 writes: >> > >> > > Martin I'd like to make a comment; I think that R's >> > > behaviour on 'edge' cases like this is an important thing >> > > and it's great that you are working on it. >> > >> > > I make heavy use of zero-extent arrays, chiefly because >> > > the dimnames are an efficient and logical way to keep >> > > track of certain types of information. >> > >> > > If I have, for example, >> > >> > > a <- array(0,c(2,0,2)) >> > > dimnames(a) <- list(name=c('Mike','Kevin'), >> > NULL,item=c("hat","scarf")) >> > >> > >> > > Then in R-3.3.1, 70800 I get >> > >> > a> 0 >> > > logical(0) >> > >> >> > >> > > But in 71219 I get >> > >> > a> 0 >> > > , , item = hat >> > >> > >> > > name >> > > Mike >> > > Kevin >> > >> > > , , item = scarf >> > >> > >> > > name >> > > Mike >> > > Kevin >> > >> > > (which is an empty logical array that holds the names of the >> people >> > and >> > > their clothes). I find the behaviour of 71219 very much preferable >> > because >> > > there is no reason to discard the information in the dimnames. >> > >> > Thanks a lot, Robin, (and Oliver) ! >> > >> > Yes, the above is such a case where the new behavior makes much sense. >> > And this behavior remains identical after the 71222 amendment. >> > >> > Martin >> > >> > > Best wishes >> > > Robin >> > >> > >> > >> > >> > > On Wed, Sep 7, 2016 at 9:49 PM, Martin Maechler < >> > maechler at stat.math.ethz.ch> >> > > wrote: >> > >> > >> >>>>> Martin Maechler <maechler at stat.math.ethz.ch> >> > >> >>>>> on Tue, 6 Sep 2016 22:26:31 +0200 writes: >> > >> >> > >> > Yesterday, changes to R's development version were committed, >> > >> relating >> > >> > to arithmetic, logic ('&' and '|') and >> > >> > comparison/relational ('<', '==') binary operators >> > >> > which in NEWS are described as >> > >> >> > >> > SIGNIFICANT USER-VISIBLE CHANGES: >> > >> >> > >> > [.............] >> > >> >> > >> > ? Arithmetic, logic (?&?, ?|?) and comparison (aka >> > >> > ?relational?, e.g., ?<?, ?==?) operations with arrays now >> > >> > behave consistently, notably for arrays of length zero. >> > >> >> > >> > Arithmetic between length-1 arrays and longer non-arrays had >> > >> > silently dropped the array attributes and recycled. This >> > >> > now gives a warning and will signal an error in the future, >> > >> > as it has always for logic and comparison operations in >> > >> > these cases (e.g., compare ?matrix(1,1) + 2:3? and >> > >> > ?matrix(1,1) < 2:3?). >> > >> >> > >> > As the above "visually suggests" one could think of the changes >> > >> > falling mainly two groups, >> > >> > 1) <0-extent array> (op) <non-array> >> > >> > 2) <1-extent array> (arith) <non-array of length != 1> >> > >> >> > >> > These changes are partly non-back compatible and may break >> > >> > existing code. We believe that the internal consistency gained >> > >> > from the changes is worth the few places with problems. >> > >> >> > >> > We expect some package maintainers (10-20, or even more?) need >> > >> > to adapt their code. >> > >> >> > >> > Case '2)' above mainly results in a new warning, e.g., >> > >> >> > >> >> matrix(1,1) + 1:2 >> > >> > [1] 2 3 >> > >> > Warning message: >> > >> > In matrix(1, 1) + 1:2 : >> > >> > dropping dim() of array of length one. Will become ERROR >> > >> >> >> > >> >> > >> > whereas '1)' gives errors in cases the result silently was a >> > >> > vector of length zero, or also keeps array (dim & dimnames) in >> > >> > cases these were silently dropped. >> > >> >> > >> > The following is a "heavily" commented R script showing (all >> ?) >> > >> > the important cases with changes : >> > >> >> > >> > ------------------------------------------------------------ >> > >> ---------------- >> > >> >> > >> > (m <- cbind(a=1[0], b=2[0])) >> > >> > Lm <- m; storage.mode(Lm) <- "logical" >> > >> > Im <- m; storage.mode(Im) <- "integer" >> > >> >> > >> > ## 1. ------------------------- >> > >> > try( m & NULL ) # in R <= 3.3.x : >> > >> > ## Error in m & NULL : >> > >> > ## operations are possible only for numeric, logical or >> complex >> > >> types >> > >> > ## >> > >> > ## gives 'Lm' in R >= 3.4.0 >> > >> >> > >> > ## 2. ------------------------- >> > >> > m + 2:3 ## gave numeric(0), now remains matrix identical to m >> > >> > Im + 2:3 ## gave integer(0), now remains matrix identical to Im >> > >> (integer) >> > >> >> > >> > m > 1 ## gave logical(0), now remains matrix identical to >> Lm >> > >> (logical) >> > >> > m > 0.1[0] ## ditto >> > >> > m > NULL ## ditto >> > >> >> > >> > ## 3. ------------------------- >> > >> > mm <- m[,c(1:2,2:1,2)] >> > >> > try( m == mm ) ## now gives error "non-conformable arrays", >> > >> > ## but gave logical(0) in R <= 3.3.x >> > >> >> > >> > ## 4. ------------------------- >> > >> > str( Im + NULL) ## gave "num", now gives "int" >> > >> >> > >> > ## 5. ------------------------- >> > >> > ## special case for arithmetic w/ length-1 array >> > >> > (m1 <- matrix(1,1,1, dimnames=list("Ro","col"))) >> > >> > (m2 <- matrix(1,2,1, dimnames=list(c("A","B"),"col"))) >> > >> >> > >> > m1 + 1:2 # -> 2:3 but now with warning to "become ERROR" >> > >> > tools::assertError(m1 & 1:2)# ERR: dims [product 1] do not >> match >> > the >> > >> length of object [2] >> > >> > tools::assertError(m1 < 1:2)# ERR: (ditto) >> > >> > ## >> > >> > ## non-0-length arrays combined with {NULL or double() or ...} >> > *fail* >> > >> >> > >> > ### Length-1 arrays: Arithmetic with |vectors| > 1 treated >> array >> > >> as scalar >> > >> > m1 + NULL # gave numeric(0) in R <= 3.3.x --- still, *but* w/ >> > >> warning to "be ERROR" >> > >> > try(m1 > NULL) # gave logical(0) in R <= 3.3.x --- an >> *error* >> > >> now in R >= 3.4.0 >> > >> > tools::assertError(m1 & NULL) # gave and gives error >> > >> > tools::assertError(m1 | double())# ditto >> > >> > ## m2 was slightly different: >> > >> > tools::assertError(m2 + NULL) >> > >> > tools::assertError(m2 & NULL) >> > >> > try(m2 == NULL) ## was logical(0) in R <= 3.3.x; now error as >> > above! >> > >> >> > >> > ------------------------------------------------------------ >> > >> ---------------- >> > >> >> > >> >> > >> > Note that in R's own 'nls' sources, there was one case of >> > >> > situation '2)' above, i.e. a 1x1-matrix was used as a >> "scalar". >> > >> >> > >> > In such cases, you should explicitly coerce it to a vector, >> > >> > either ("self-explainingly") by as.vector(.), or as I did in >> > >> > the nls case by c(.) : The latter is much less >> > >> > self-explaining, but nicer to read in mathematical formulae, >> and >> > >> > currently also more efficient because it is a .Primitive. >> > >> >> > >> > Please use R-devel with your code, and let us know if you see >> > >> > effects that seem adverse. >> > >> >> > >> I've been slightly surprised (or even "frustrated") by the empty >> > >> reaction on our R-devel list to this post. >> > >> >> > >> I would have expected some critique, may be even some praise, >> > >> ... in any case some sign people are "thinking along" (as we say >> > >> in German). >> > >> >> > >> In the mean time, I've actually thought along the one case which >> > >> is last above: The <op> (binary operation) between a >> > >> non-0-length array and a 0-length vector (and NULL which should >> > >> be treated like a 0-length vector): >> > >> >> > >> R <= 3.3.1 *is* quite inconsistent with these: >> > >> >> > >> >> > >> and my proposal above (implemented in R-devel, since Sep.5) would >> > give an >> > >> error for all these, but instead, R really could be more lenient >> > here: >> > >> A 0-length result is ok, and it should *not* inherit the array >> > >> (dim, dimnames), since the array is not of length 0. So instead >> > >> of the above [for the very last part only!!], we would aim for >> > >> the following. These *all* give an error in current R-devel, >> > >> with the exception of 'm1 + NULL' which "only" gives a "bad >> > >> warning" : >> > >> >> > >> ------------------------ >> > >> >> > >> m1 <- matrix(1,1) >> > >> m2 <- matrix(1,2) >> > >> >> > >> m1 + NULL # numeric(0) in R <= 3.3.x ---> OK ?! >> > >> m1 > NULL # logical(0) in R <= 3.3.x ---> OK ?! >> > >> try(m1 & NULL) # ERROR in R <= 3.3.x ---> change to logical(0) >> > ?! >> > >> try(m1 | double())# ERROR in R <= 3.3.x ---> change to logical(0) >> > ?! >> > >> ## m2 slightly different: >> > >> try(m2 + NULL) # ERROR in R <= 3.3.x ---> change to double(0) >> ?! >> > >> try(m2 & NULL) # ERROR in R <= 3.3.x ---> change to logical(0) >> ?! >> > >> m2 == NULL # logical(0) in R <= 3.3.x ---> OK ?! >> > >> >> > >> ------------------------ >> > >> >> > >> This would be slightly more back-compatible than the currently >> > >> implemented proposal. Everything else I said remains true, and >> > >> I'm pretty sure most changes needed in packages would remain to >> be >> > done. >> > >> >> > >> Opinions ? >> > >> >> > >> >> > >> >> > >> > In some case where R-devel now gives an error but did not >> > >> > previously, we could contemplate giving another "warning >> > >> > .... 'to become ERROR'" if there was too much breakage, though >> > >> > I don't expect that. >> > >> >> > >> >> > >> > For the R Core Team, >> > >> >> > >> > Martin Maechler, >> > >> > ETH Zurich >> > >> >> > >> ______________________________________________ >> > >> R-devel at r-project.org mailing list >> > >> https://stat.ethz.ch/mailman/listinfo/r-devel >> > >> >> > >> > >> > >> > > -- >> > > Robin Hankin >> > > Neutral theorist >> > > hankin.robin at gmail.com >> > >> > > [[alternative HTML version deleted]] >> > >> > ______________________________________________ >> > 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]] >> >> ______________________________________________ >> 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]]
William Dunlap
2016-Sep-08 17:45 UTC
[Rd] R (development) changes in arith, logic, relop with (0-extent) arrays
Prior to the mid-1990s, S did "length-0 OP length-n -> rep(NA, n)" and it was changed to "length-0 OP length-n -> length-0" to avoid lots of problems like any(x<0) being NA when length(x)==0. Yes, people could code defensively by putting lots of if(length(x)==0)... in their code, but that is tedious and error-prone and creates really ugly code. Is your suggestion to leave the length-0 OP length-1 case as it is but make length-0 OP length-two-or-higher an error or warning (akin to the length-2 OP length-3 case)? By the way, the all(numeric(0)<0) is TRUE, as is all(numeric()>0), by de Morgan's rule, but that is not really relevant here. Bill Dunlap TIBCO Software wdunlap tibco.com On Thu, Sep 8, 2016 at 10:22 AM, Gabriel Becker <gmbecker at ucdavis.edu> wrote:> > > On Thu, Sep 8, 2016 at 10:05 AM, William Dunlap <wdunlap at tibco.com> wrote: > >> Shouldn't binary operators (arithmetic and logical) should throw an error >> when one operand is NULL (or other type that doesn't make sense)? This is >> a different case than a zero-length operand of a legitimate type. E.g., >> any(x < 0) >> should return FALSE if x is number-like and length(x)==0 but give an >> error if x is NULL. >> > Bill, > > That is a good point. I can see the argument for this in the case that the > non-zero length is 1. I'm not sure which is better though. If we switch > any() to all(), things get murky. > > Mathematically, all(x<0) is TRUE if x is length 0 (as are all(x==0), and > all(x>0)), but the likelihood of this being a thought-bug on the author's > part is exceedingly high, imho. So the desirable behavior seems to depend > on the angle we look at it from. > > My personal opinion is that x < y with length(x)==0 should fail if length(y) > > 1, at least, and I'd be for it being an error even if y is length 1, > though I do acknowledge this is more likely (though still quite unlikely > imho) to be the intended behavior. > > ~G > >> >> I.e., I think the type check should be done before the length check. >> >> >> Bill Dunlap >> TIBCO Software >> wdunlap tibco.com >> >> On Thu, Sep 8, 2016 at 8:43 AM, Gabriel Becker <gmbecker at ucdavis.edu> >> wrote: >> >>> Martin, >>> >>> Like Robin and Oliver I think this type of edge-case consistency is >>> important and that it's fantastic that R-core - and you personally - are >>> willing to tackle some of these "gotcha" behaviors. "Little" stuff like >>> this really does combine to go a long way to making R better and better. >>> >>> I do wonder a bit about the >>> >>> x = 1:2 >>> >>> y = NULL >>> >>> x < y >>> >>> case. >>> >>> Returning a logical of length 0 is more backwards compatible, but is it >>> ever what the author actually intended? I have trouble thinking of a case >>> where that less-than didn't carry an implicit assumption that y was >>> non-NULL. I can say that in my own code, I've never hit that behavior >>> in a >>> case that wasn't an error. >>> >>> My vote (unless someone else points out a compelling use for the >>> behavior) >>> is for the to throw an error. As a developer, I'd rather things like this >>> break so the bug in my logic is visible, rather than propagating as the >>> 0-length logical is &'ed or |'ed with other logical vectors, or used to >>> subset, or (in the case it should be length 1) passed to if() (if throws >>> an >>> error now, but the rest would silently "work"). >>> >>> Best, >>> ~G >>> >>> On Thu, Sep 8, 2016 at 3:49 AM, Martin Maechler < >>> maechler at stat.math.ethz.ch> >>> wrote: >>> >>> > >>>>> robin hankin <hankin.robin at gmail.com> >>> > >>>>> on Thu, 8 Sep 2016 10:05:21 +1200 writes: >>> > >>> > > Martin I'd like to make a comment; I think that R's >>> > > behaviour on 'edge' cases like this is an important thing >>> > > and it's great that you are working on it. >>> > >>> > > I make heavy use of zero-extent arrays, chiefly because >>> > > the dimnames are an efficient and logical way to keep >>> > > track of certain types of information. >>> > >>> > > If I have, for example, >>> > >>> > > a <- array(0,c(2,0,2)) >>> > > dimnames(a) <- list(name=c('Mike','Kevin'), >>> > NULL,item=c("hat","scarf")) >>> > >>> > >>> > > Then in R-3.3.1, 70800 I get >>> > >>> > a> 0 >>> > > logical(0) >>> > >> >>> > >>> > > But in 71219 I get >>> > >>> > a> 0 >>> > > , , item = hat >>> > >>> > >>> > > name >>> > > Mike >>> > > Kevin >>> > >>> > > , , item = scarf >>> > >>> > >>> > > name >>> > > Mike >>> > > Kevin >>> > >>> > > (which is an empty logical array that holds the names of the >>> people >>> > and >>> > > their clothes). I find the behaviour of 71219 very much >>> preferable >>> > because >>> > > there is no reason to discard the information in the dimnames. >>> > >>> > Thanks a lot, Robin, (and Oliver) ! >>> > >>> > Yes, the above is such a case where the new behavior makes much sense. >>> > And this behavior remains identical after the 71222 amendment. >>> > >>> > Martin >>> > >>> > > Best wishes >>> > > Robin >>> > >>> > >>> > >>> > >>> > > On Wed, Sep 7, 2016 at 9:49 PM, Martin Maechler < >>> > maechler at stat.math.ethz.ch> >>> > > wrote: >>> > >>> > >> >>>>> Martin Maechler <maechler at stat.math.ethz.ch> >>> > >> >>>>> on Tue, 6 Sep 2016 22:26:31 +0200 writes: >>> > >> >>> > >> > Yesterday, changes to R's development version were committed, >>> > >> relating >>> > >> > to arithmetic, logic ('&' and '|') and >>> > >> > comparison/relational ('<', '==') binary operators >>> > >> > which in NEWS are described as >>> > >> >>> > >> > SIGNIFICANT USER-VISIBLE CHANGES: >>> > >> >>> > >> > [.............] >>> > >> >>> > >> > ? Arithmetic, logic (?&?, ?|?) and comparison (aka >>> > >> > ?relational?, e.g., ?<?, ?==?) operations with arrays now >>> > >> > behave consistently, notably for arrays of length zero. >>> > >> >>> > >> > Arithmetic between length-1 arrays and longer non-arrays had >>> > >> > silently dropped the array attributes and recycled. This >>> > >> > now gives a warning and will signal an error in the future, >>> > >> > as it has always for logic and comparison operations in >>> > >> > these cases (e.g., compare ?matrix(1,1) + 2:3? and >>> > >> > ?matrix(1,1) < 2:3?). >>> > >> >>> > >> > As the above "visually suggests" one could think of the >>> changes >>> > >> > falling mainly two groups, >>> > >> > 1) <0-extent array> (op) <non-array> >>> > >> > 2) <1-extent array> (arith) <non-array of length != 1> >>> > >> >>> > >> > These changes are partly non-back compatible and may break >>> > >> > existing code. We believe that the internal consistency >>> gained >>> > >> > from the changes is worth the few places with problems. >>> > >> >>> > >> > We expect some package maintainers (10-20, or even more?) need >>> > >> > to adapt their code. >>> > >> >>> > >> > Case '2)' above mainly results in a new warning, e.g., >>> > >> >>> > >> >> matrix(1,1) + 1:2 >>> > >> > [1] 2 3 >>> > >> > Warning message: >>> > >> > In matrix(1, 1) + 1:2 : >>> > >> > dropping dim() of array of length one. Will become ERROR >>> > >> >> >>> > >> >>> > >> > whereas '1)' gives errors in cases the result silently was a >>> > >> > vector of length zero, or also keeps array (dim & dimnames) in >>> > >> > cases these were silently dropped. >>> > >> >>> > >> > The following is a "heavily" commented R script showing (all >>> ?) >>> > >> > the important cases with changes : >>> > >> >>> > >> > ------------------------------------------------------------ >>> > >> ---------------- >>> > >> >>> > >> > (m <- cbind(a=1[0], b=2[0])) >>> > >> > Lm <- m; storage.mode(Lm) <- "logical" >>> > >> > Im <- m; storage.mode(Im) <- "integer" >>> > >> >>> > >> > ## 1. ------------------------- >>> > >> > try( m & NULL ) # in R <= 3.3.x : >>> > >> > ## Error in m & NULL : >>> > >> > ## operations are possible only for numeric, logical or >>> complex >>> > >> types >>> > >> > ## >>> > >> > ## gives 'Lm' in R >= 3.4.0 >>> > >> >>> > >> > ## 2. ------------------------- >>> > >> > m + 2:3 ## gave numeric(0), now remains matrix identical to m >>> > >> > Im + 2:3 ## gave integer(0), now remains matrix identical to >>> Im >>> > >> (integer) >>> > >> >>> > >> > m > 1 ## gave logical(0), now remains matrix identical >>> to Lm >>> > >> (logical) >>> > >> > m > 0.1[0] ## ditto >>> > >> > m > NULL ## ditto >>> > >> >>> > >> > ## 3. ------------------------- >>> > >> > mm <- m[,c(1:2,2:1,2)] >>> > >> > try( m == mm ) ## now gives error "non-conformable arrays", >>> > >> > ## but gave logical(0) in R <= 3.3.x >>> > >> >>> > >> > ## 4. ------------------------- >>> > >> > str( Im + NULL) ## gave "num", now gives "int" >>> > >> >>> > >> > ## 5. ------------------------- >>> > >> > ## special case for arithmetic w/ length-1 array >>> > >> > (m1 <- matrix(1,1,1, dimnames=list("Ro","col"))) >>> > >> > (m2 <- matrix(1,2,1, dimnames=list(c("A","B"),"col"))) >>> > >> >>> > >> > m1 + 1:2 # -> 2:3 but now with warning to "become ERROR" >>> > >> > tools::assertError(m1 & 1:2)# ERR: dims [product 1] do not >>> match >>> > the >>> > >> length of object [2] >>> > >> > tools::assertError(m1 < 1:2)# ERR: (ditto) >>> > >> > ## >>> > >> > ## non-0-length arrays combined with {NULL or double() or ...} >>> > *fail* >>> > >> >>> > >> > ### Length-1 arrays: Arithmetic with |vectors| > 1 treated >>> array >>> > >> as scalar >>> > >> > m1 + NULL # gave numeric(0) in R <= 3.3.x --- still, *but* w/ >>> > >> warning to "be ERROR" >>> > >> > try(m1 > NULL) # gave logical(0) in R <= 3.3.x --- an >>> *error* >>> > >> now in R >= 3.4.0 >>> > >> > tools::assertError(m1 & NULL) # gave and gives error >>> > >> > tools::assertError(m1 | double())# ditto >>> > >> > ## m2 was slightly different: >>> > >> > tools::assertError(m2 + NULL) >>> > >> > tools::assertError(m2 & NULL) >>> > >> > try(m2 == NULL) ## was logical(0) in R <= 3.3.x; now error as >>> > above! >>> > >> >>> > >> > ------------------------------------------------------------ >>> > >> ---------------- >>> > >> >>> > >> >>> > >> > Note that in R's own 'nls' sources, there was one case of >>> > >> > situation '2)' above, i.e. a 1x1-matrix was used as a >>> "scalar". >>> > >> >>> > >> > In such cases, you should explicitly coerce it to a vector, >>> > >> > either ("self-explainingly") by as.vector(.), or as I did in >>> > >> > the nls case by c(.) : The latter is much less >>> > >> > self-explaining, but nicer to read in mathematical formulae, >>> and >>> > >> > currently also more efficient because it is a .Primitive. >>> > >> >>> > >> > Please use R-devel with your code, and let us know if you see >>> > >> > effects that seem adverse. >>> > >> >>> > >> I've been slightly surprised (or even "frustrated") by the empty >>> > >> reaction on our R-devel list to this post. >>> > >> >>> > >> I would have expected some critique, may be even some praise, >>> > >> ... in any case some sign people are "thinking along" (as we say >>> > >> in German). >>> > >> >>> > >> In the mean time, I've actually thought along the one case which >>> > >> is last above: The <op> (binary operation) between a >>> > >> non-0-length array and a 0-length vector (and NULL which should >>> > >> be treated like a 0-length vector): >>> > >> >>> > >> R <= 3.3.1 *is* quite inconsistent with these: >>> > >> >>> > >> >>> > >> and my proposal above (implemented in R-devel, since Sep.5) >>> would >>> > give an >>> > >> error for all these, but instead, R really could be more lenient >>> > here: >>> > >> A 0-length result is ok, and it should *not* inherit the array >>> > >> (dim, dimnames), since the array is not of length 0. So instead >>> > >> of the above [for the very last part only!!], we would aim for >>> > >> the following. These *all* give an error in current R-devel, >>> > >> with the exception of 'm1 + NULL' which "only" gives a "bad >>> > >> warning" : >>> > >> >>> > >> ------------------------ >>> > >> >>> > >> m1 <- matrix(1,1) >>> > >> m2 <- matrix(1,2) >>> > >> >>> > >> m1 + NULL # numeric(0) in R <= 3.3.x ---> OK ?! >>> > >> m1 > NULL # logical(0) in R <= 3.3.x ---> OK ?! >>> > >> try(m1 & NULL) # ERROR in R <= 3.3.x ---> change to >>> logical(0) >>> > ?! >>> > >> try(m1 | double())# ERROR in R <= 3.3.x ---> change to >>> logical(0) >>> > ?! >>> > >> ## m2 slightly different: >>> > >> try(m2 + NULL) # ERROR in R <= 3.3.x ---> change to double(0) >>> ?! >>> > >> try(m2 & NULL) # ERROR in R <= 3.3.x ---> change to >>> logical(0) ?! >>> > >> m2 == NULL # logical(0) in R <= 3.3.x ---> OK ?! >>> > >> >>> > >> ------------------------ >>> > >> >>> > >> This would be slightly more back-compatible than the currently >>> > >> implemented proposal. Everything else I said remains true, and >>> > >> I'm pretty sure most changes needed in packages would remain to >>> be >>> > done. >>> > >> >>> > >> Opinions ? >>> > >> >>> > >> >>> > >> >>> > >> > In some case where R-devel now gives an error but did not >>> > >> > previously, we could contemplate giving another "warning >>> > >> > .... 'to become ERROR'" if there was too much breakage, >>> though >>> > >> > I don't expect that. >>> > >> >>> > >> >>> > >> > For the R Core Team, >>> > >> >>> > >> > Martin Maechler, >>> > >> > ETH Zurich >>> > >> >>> > >> ______________________________________________ >>> > >> R-devel at r-project.org mailing list >>> > >> https://stat.ethz.ch/mailman/listinfo/r-devel >>> > >> >>> > >>> > >>> > >>> > > -- >>> > > Robin Hankin >>> > > Neutral theorist >>> > > hankin.robin at gmail.com >>> > >>> > > [[alternative HTML version deleted]] >>> > >>> > ______________________________________________ >>> > 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]] >>> >>> ______________________________________________ >>> 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]]
Paul Gilbert
2016-Sep-08 18:00 UTC
[Rd] R (development) changes in arith, logic, relop with (0-extent) arrays
On 09/08/2016 01:22 PM, Gabriel Becker wrote:> On Thu, Sep 8, 2016 at 10:05 AM, William Dunlap <wdunlap at tibco.com> wrote: > >> Shouldn't binary operators (arithmetic and logical) should throw an error >> when one operand is NULL (or other type that doesn't make sense)? This is >> a different case than a zero-length operand of a legitimate type. E.g., >> any(x < 0) >> should return FALSE if x is number-like and length(x)==0 but give an error >> if x is NULL. >> > Bill, > > That is a good point. I can see the argument for this in the case that the > non-zero length is 1. I'm not sure which is better though. If we switch > any() to all(), things get murky. > > Mathematically, all(x<0) is TRUE if x is length 0 (as are all(x==0), and > all(x>0)), but the likelihood of this being a thought-bug on the author's > part is exceedingly high, imho.I suspect there may be more R users than you think that understand and use vacuously true in code. I don't really like the idea of turning a perfectly good and properly documented mathematical test into an error in order to protect against a possible "thought-bug". Paul So the desirable behavior seems to depend> on the angle we look at it from. > > My personal opinion is that x < y with length(x)==0 should fail if length(y) >> 1, at least, and I'd be for it being an error even if y is length 1, > though I do acknowledge this is more likely (though still quite unlikely > imho) to be the intended behavior. > > ~G > >> >> I.e., I think the type check should be done before the length check. >> >> >> Bill Dunlap >> TIBCO Software >> wdunlap tibco.com >> >> On Thu, Sep 8, 2016 at 8:43 AM, Gabriel Becker <gmbecker at ucdavis.edu> >> wrote: >> >>> Martin, >>> >>> Like Robin and Oliver I think this type of edge-case consistency is >>> important and that it's fantastic that R-core - and you personally - are >>> willing to tackle some of these "gotcha" behaviors. "Little" stuff like >>> this really does combine to go a long way to making R better and better. >>> >>> I do wonder a bit about the >>> >>> x = 1:2 >>> >>> y = NULL >>> >>> x < y >>> >>> case. >>> >>> Returning a logical of length 0 is more backwards compatible, but is it >>> ever what the author actually intended? I have trouble thinking of a case >>> where that less-than didn't carry an implicit assumption that y was >>> non-NULL. I can say that in my own code, I've never hit that behavior in >>> a >>> case that wasn't an error. >>> >>> My vote (unless someone else points out a compelling use for the behavior) >>> is for the to throw an error. As a developer, I'd rather things like this >>> break so the bug in my logic is visible, rather than propagating as the >>> 0-length logical is &'ed or |'ed with other logical vectors, or used to >>> subset, or (in the case it should be length 1) passed to if() (if throws >>> an >>> error now, but the rest would silently "work"). >>> >>> Best, >>> ~G >>> >>> On Thu, Sep 8, 2016 at 3:49 AM, Martin Maechler < >>> maechler at stat.math.ethz.ch> >>> wrote: >>> >>>>>>>>> robin hankin <hankin.robin at gmail.com> >>>>>>>>> on Thu, 8 Sep 2016 10:05:21 +1200 writes: >>>> >>>> > Martin I'd like to make a comment; I think that R's >>>> > behaviour on 'edge' cases like this is an important thing >>>> > and it's great that you are working on it. >>>> >>>> > I make heavy use of zero-extent arrays, chiefly because >>>> > the dimnames are an efficient and logical way to keep >>>> > track of certain types of information. >>>> >>>> > If I have, for example, >>>> >>>> > a <- array(0,c(2,0,2)) >>>> > dimnames(a) <- list(name=c('Mike','Kevin'), >>>> NULL,item=c("hat","scarf")) >>>> >>>> >>>> > Then in R-3.3.1, 70800 I get >>>> >>>> a> 0 >>>> > logical(0) >>>> >> >>>> >>>> > But in 71219 I get >>>> >>>> a> 0 >>>> > , , item = hat >>>> >>>> >>>> > name >>>> > Mike >>>> > Kevin >>>> >>>> > , , item = scarf >>>> >>>> >>>> > name >>>> > Mike >>>> > Kevin >>>> >>>> > (which is an empty logical array that holds the names of the >>> people >>>> and >>>> > their clothes). I find the behaviour of 71219 very much preferable >>>> because >>>> > there is no reason to discard the information in the dimnames. >>>> >>>> Thanks a lot, Robin, (and Oliver) ! >>>> >>>> Yes, the above is such a case where the new behavior makes much sense. >>>> And this behavior remains identical after the 71222 amendment. >>>> >>>> Martin >>>> >>>> > Best wishes >>>> > Robin >>>> >>>> >>>> >>>> >>>> > On Wed, Sep 7, 2016 at 9:49 PM, Martin Maechler < >>>> maechler at stat.math.ethz.ch> >>>> > wrote: >>>> >>>> >> >>>>> Martin Maechler <maechler at stat.math.ethz.ch> >>>> >> >>>>> on Tue, 6 Sep 2016 22:26:31 +0200 writes: >>>> >> >>>> >> > Yesterday, changes to R's development version were committed, >>>> >> relating >>>> >> > to arithmetic, logic ('&' and '|') and >>>> >> > comparison/relational ('<', '==') binary operators >>>> >> > which in NEWS are described as >>>> >> >>>> >> > SIGNIFICANT USER-VISIBLE CHANGES: >>>> >> >>>> >> > [.............] >>>> >> >>>> >> > ? Arithmetic, logic (?&?, ?|?) and comparison (aka >>>> >> > ?relational?, e.g., ?<?, ?==?) operations with arrays now >>>> >> > behave consistently, notably for arrays of length zero. >>>> >> >>>> >> > Arithmetic between length-1 arrays and longer non-arrays had >>>> >> > silently dropped the array attributes and recycled. This >>>> >> > now gives a warning and will signal an error in the future, >>>> >> > as it has always for logic and comparison operations in >>>> >> > these cases (e.g., compare ?matrix(1,1) + 2:3? and >>>> >> > ?matrix(1,1) < 2:3?). >>>> >> >>>> >> > As the above "visually suggests" one could think of the changes >>>> >> > falling mainly two groups, >>>> >> > 1) <0-extent array> (op) <non-array> >>>> >> > 2) <1-extent array> (arith) <non-array of length != 1> >>>> >> >>>> >> > These changes are partly non-back compatible and may break >>>> >> > existing code. We believe that the internal consistency gained >>>> >> > from the changes is worth the few places with problems. >>>> >> >>>> >> > We expect some package maintainers (10-20, or even more?) need >>>> >> > to adapt their code. >>>> >> >>>> >> > Case '2)' above mainly results in a new warning, e.g., >>>> >> >>>> >> >> matrix(1,1) + 1:2 >>>> >> > [1] 2 3 >>>> >> > Warning message: >>>> >> > In matrix(1, 1) + 1:2 : >>>> >> > dropping dim() of array of length one. Will become ERROR >>>> >> >> >>>> >> >>>> >> > whereas '1)' gives errors in cases the result silently was a >>>> >> > vector of length zero, or also keeps array (dim & dimnames) in >>>> >> > cases these were silently dropped. >>>> >> >>>> >> > The following is a "heavily" commented R script showing (all >>> ?) >>>> >> > the important cases with changes : >>>> >> >>>> >> > ------------------------------------------------------------ >>>> >> ---------------- >>>> >> >>>> >> > (m <- cbind(a=1[0], b=2[0])) >>>> >> > Lm <- m; storage.mode(Lm) <- "logical" >>>> >> > Im <- m; storage.mode(Im) <- "integer" >>>> >> >>>> >> > ## 1. ------------------------- >>>> >> > try( m & NULL ) # in R <= 3.3.x : >>>> >> > ## Error in m & NULL : >>>> >> > ## operations are possible only for numeric, logical or >>> complex >>>> >> types >>>> >> > ## >>>> >> > ## gives 'Lm' in R >= 3.4.0 >>>> >> >>>> >> > ## 2. ------------------------- >>>> >> > m + 2:3 ## gave numeric(0), now remains matrix identical to m >>>> >> > Im + 2:3 ## gave integer(0), now remains matrix identical to Im >>>> >> (integer) >>>> >> >>>> >> > m > 1 ## gave logical(0), now remains matrix identical to >>> Lm >>>> >> (logical) >>>> >> > m > 0.1[0] ## ditto >>>> >> > m > NULL ## ditto >>>> >> >>>> >> > ## 3. ------------------------- >>>> >> > mm <- m[,c(1:2,2:1,2)] >>>> >> > try( m == mm ) ## now gives error "non-conformable arrays", >>>> >> > ## but gave logical(0) in R <= 3.3.x >>>> >> >>>> >> > ## 4. ------------------------- >>>> >> > str( Im + NULL) ## gave "num", now gives "int" >>>> >> >>>> >> > ## 5. ------------------------- >>>> >> > ## special case for arithmetic w/ length-1 array >>>> >> > (m1 <- matrix(1,1,1, dimnames=list("Ro","col"))) >>>> >> > (m2 <- matrix(1,2,1, dimnames=list(c("A","B"),"col"))) >>>> >> >>>> >> > m1 + 1:2 # -> 2:3 but now with warning to "become ERROR" >>>> >> > tools::assertError(m1 & 1:2)# ERR: dims [product 1] do not >>> match >>>> the >>>> >> length of object [2] >>>> >> > tools::assertError(m1 < 1:2)# ERR: (ditto) >>>> >> > ## >>>> >> > ## non-0-length arrays combined with {NULL or double() or ...} >>>> *fail* >>>> >> >>>> >> > ### Length-1 arrays: Arithmetic with |vectors| > 1 treated >>> array >>>> >> as scalar >>>> >> > m1 + NULL # gave numeric(0) in R <= 3.3.x --- still, *but* w/ >>>> >> warning to "be ERROR" >>>> >> > try(m1 > NULL) # gave logical(0) in R <= 3.3.x --- an >>> *error* >>>> >> now in R >= 3.4.0 >>>> >> > tools::assertError(m1 & NULL) # gave and gives error >>>> >> > tools::assertError(m1 | double())# ditto >>>> >> > ## m2 was slightly different: >>>> >> > tools::assertError(m2 + NULL) >>>> >> > tools::assertError(m2 & NULL) >>>> >> > try(m2 == NULL) ## was logical(0) in R <= 3.3.x; now error as >>>> above! >>>> >> >>>> >> > ------------------------------------------------------------ >>>> >> ---------------- >>>> >> >>>> >> >>>> >> > Note that in R's own 'nls' sources, there was one case of >>>> >> > situation '2)' above, i.e. a 1x1-matrix was used as a >>> "scalar". >>>> >> >>>> >> > In such cases, you should explicitly coerce it to a vector, >>>> >> > either ("self-explainingly") by as.vector(.), or as I did in >>>> >> > the nls case by c(.) : The latter is much less >>>> >> > self-explaining, but nicer to read in mathematical formulae, >>> and >>>> >> > currently also more efficient because it is a .Primitive. >>>> >> >>>> >> > Please use R-devel with your code, and let us know if you see >>>> >> > effects that seem adverse. >>>> >> >>>> >> I've been slightly surprised (or even "frustrated") by the empty >>>> >> reaction on our R-devel list to this post. >>>> >> >>>> >> I would have expected some critique, may be even some praise, >>>> >> ... in any case some sign people are "thinking along" (as we say >>>> >> in German). >>>> >> >>>> >> In the mean time, I've actually thought along the one case which >>>> >> is last above: The <op> (binary operation) between a >>>> >> non-0-length array and a 0-length vector (and NULL which should >>>> >> be treated like a 0-length vector): >>>> >> >>>> >> R <= 3.3.1 *is* quite inconsistent with these: >>>> >> >>>> >> >>>> >> and my proposal above (implemented in R-devel, since Sep.5) would >>>> give an >>>> >> error for all these, but instead, R really could be more lenient >>>> here: >>>> >> A 0-length result is ok, and it should *not* inherit the array >>>> >> (dim, dimnames), since the array is not of length 0. So instead >>>> >> of the above [for the very last part only!!], we would aim for >>>> >> the following. These *all* give an error in current R-devel, >>>> >> with the exception of 'm1 + NULL' which "only" gives a "bad >>>> >> warning" : >>>> >> >>>> >> ------------------------ >>>> >> >>>> >> m1 <- matrix(1,1) >>>> >> m2 <- matrix(1,2) >>>> >> >>>> >> m1 + NULL # numeric(0) in R <= 3.3.x ---> OK ?! >>>> >> m1 > NULL # logical(0) in R <= 3.3.x ---> OK ?! >>>> >> try(m1 & NULL) # ERROR in R <= 3.3.x ---> change to logical(0) >>>> ?! >>>> >> try(m1 | double())# ERROR in R <= 3.3.x ---> change to logical(0) >>>> ?! >>>> >> ## m2 slightly different: >>>> >> try(m2 + NULL) # ERROR in R <= 3.3.x ---> change to double(0) >>> ?! >>>> >> try(m2 & NULL) # ERROR in R <= 3.3.x ---> change to logical(0) >>> ?! >>>> >> m2 == NULL # logical(0) in R <= 3.3.x ---> OK ?! >>>> >> >>>> >> ------------------------ >>>> >> >>>> >> This would be slightly more back-compatible than the currently >>>> >> implemented proposal. Everything else I said remains true, and >>>> >> I'm pretty sure most changes needed in packages would remain to >>> be >>>> done. >>>> >> >>>> >> Opinions ? >>>> >> >>>> >> >>>> >> >>>> >> > In some case where R-devel now gives an error but did not >>>> >> > previously, we could contemplate giving another "warning >>>> >> > .... 'to become ERROR'" if there was too much breakage, though >>>> >> > I don't expect that. >>>> >> >>>> >> >>>> >> > For the R Core Team, >>>> >> >>>> >> > Martin Maechler, >>>> >> > ETH Zurich >>>> >> >>>> >> ______________________________________________ >>>> >> R-devel at r-project.org mailing list >>>> >> https://stat.ethz.ch/mailman/listinfo/r-devel >>>> >> >>>> >>>> >>>> >>>> > -- >>>> > Robin Hankin >>>> > Neutral theorist >>>> > hankin.robin at gmail.com >>>> >>>> > [[alternative HTML version deleted]] >>>> >>>> ______________________________________________ >>>> 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]] >>> >>> ______________________________________________ >>> R-devel at r-project.org mailing list >>> https://stat.ethz.ch/mailman/listinfo/r-devel >>> >> >> > >
robin hankin
2016-Sep-08 21:06 UTC
[Rd] R (development) changes in arith, logic, relop with (0-extent) arrays
Could we take a cue from min() and max()?> x <- 1:10 > min(x[x>7])[1] 8> min(x[x>11])[1] Inf Warning message: In min(x[x > 11]) : no non-missing arguments to min; returning Inf>As ?min says, this is implemented to preserve transitivity, and this makes a lot of sense. I think the issuing of a warning here is a good compromise; I can always turn off warnings if I want. I find this behaviour of min() and max() to be annoying in the *right* way: it annoys me precisely when I need to be annoyed, that is, when I haven't thought through the consequences of sending zero-length arguments. On Fri, Sep 9, 2016 at 6:00 AM, Paul Gilbert <pgilbert902 at gmail.com> wrote:> > > On 09/08/2016 01:22 PM, Gabriel Becker wrote: >> >> On Thu, Sep 8, 2016 at 10:05 AM, William Dunlap <wdunlap at tibco.com> wrote: >> >>> Shouldn't binary operators (arithmetic and logical) should throw an error >>> when one operand is NULL (or other type that doesn't make sense)? This >>> is >>> a different case than a zero-length operand of a legitimate type. E.g., >>> any(x < 0) >>> should return FALSE if x is number-like and length(x)==0 but give an >>> error >>> if x is NULL. >>> >> Bill, >> >> That is a good point. I can see the argument for this in the case that the >> non-zero length is 1. I'm not sure which is better though. If we switch >> any() to all(), things get murky. >> >> Mathematically, all(x<0) is TRUE if x is length 0 (as are all(x==0), and >> all(x>0)), but the likelihood of this being a thought-bug on the author's >> part is exceedingly high, imho. > > > I suspect there may be more R users than you think that understand and use > vacuously true in code. I don't really like the idea of turning a perfectly > good and properly documented mathematical test into an error in order to > protect against a possible "thought-bug". > > Paul > > > So the desirable behavior seems to depend >> >> on the angle we look at it from. >> >> My personal opinion is that x < y with length(x)==0 should fail if >> length(y) >>> >>> 1, at least, and I'd be for it being an error even if y is length 1, >> >> though I do acknowledge this is more likely (though still quite unlikely >> imho) to be the intended behavior. >> >> ~G >> >>> >>> I.e., I think the type check should be done before the length check. >>> >>> >>> Bill Dunlap >>> TIBCO Software >>> wdunlap tibco.com >>> >>> On Thu, Sep 8, 2016 at 8:43 AM, Gabriel Becker <gmbecker at ucdavis.edu> >>> wrote: >>> >>>> Martin, >>>> >>>> Like Robin and Oliver I think this type of edge-case consistency is >>>> important and that it's fantastic that R-core - and you personally - are >>>> willing to tackle some of these "gotcha" behaviors. "Little" stuff like >>>> this really does combine to go a long way to making R better and better. >>>> >>>> I do wonder a bit about the >>>> >>>> x = 1:2 >>>> >>>> y = NULL >>>> >>>> x < y >>>> >>>> case. >>>> >>>> Returning a logical of length 0 is more backwards compatible, but is it >>>> ever what the author actually intended? I have trouble thinking of a >>>> case >>>> where that less-than didn't carry an implicit assumption that y was >>>> non-NULL. I can say that in my own code, I've never hit that behavior >>>> in >>>> a >>>> case that wasn't an error. >>>> >>>> My vote (unless someone else points out a compelling use for the >>>> behavior) >>>> is for the to throw an error. As a developer, I'd rather things like >>>> this >>>> break so the bug in my logic is visible, rather than propagating as the >>>> 0-length logical is &'ed or |'ed with other logical vectors, or used to >>>> subset, or (in the case it should be length 1) passed to if() (if throws >>>> an >>>> error now, but the rest would silently "work"). >>>> >>>> Best, >>>> ~G >>>> >>>> On Thu, Sep 8, 2016 at 3:49 AM, Martin Maechler < >>>> maechler at stat.math.ethz.ch> >>>> wrote: >>>> >>>>>>>>>> robin hankin <hankin.robin at gmail.com> >>>>>>>>>> on Thu, 8 Sep 2016 10:05:21 +1200 writes: >>>>> >>>>> >>>>> > Martin I'd like to make a comment; I think that R's >>>>> > behaviour on 'edge' cases like this is an important thing >>>>> > and it's great that you are working on it. >>>>> >>>>> > I make heavy use of zero-extent arrays, chiefly because >>>>> > the dimnames are an efficient and logical way to keep >>>>> > track of certain types of information. >>>>> >>>>> > If I have, for example, >>>>> >>>>> > a <- array(0,c(2,0,2)) >>>>> > dimnames(a) <- list(name=c('Mike','Kevin'), >>>>> NULL,item=c("hat","scarf")) >>>>> >>>>> >>>>> > Then in R-3.3.1, 70800 I get >>>>> >>>>> a> 0 >>>>> > logical(0) >>>>> >> >>>>> >>>>> > But in 71219 I get >>>>> >>>>> a> 0 >>>>> > , , item = hat >>>>> >>>>> >>>>> > name >>>>> > Mike >>>>> > Kevin >>>>> >>>>> > , , item = scarf >>>>> >>>>> >>>>> > name >>>>> > Mike >>>>> > Kevin >>>>> >>>>> > (which is an empty logical array that holds the names of the >>>> >>>> people >>>>> >>>>> and >>>>> > their clothes). I find the behaviour of 71219 very much >>>>> preferable >>>>> because >>>>> > there is no reason to discard the information in the dimnames. >>>>> >>>>> Thanks a lot, Robin, (and Oliver) ! >>>>> >>>>> Yes, the above is such a case where the new behavior makes much sense. >>>>> And this behavior remains identical after the 71222 amendment. >>>>> >>>>> Martin >>>>> >>>>> > Best wishes >>>>> > Robin >>>>> >>>>> >>>>> >>>>> >>>>> > On Wed, Sep 7, 2016 at 9:49 PM, Martin Maechler < >>>>> maechler at stat.math.ethz.ch> >>>>> > wrote: >>>>> >>>>> >> >>>>> Martin Maechler <maechler at stat.math.ethz.ch> >>>>> >> >>>>> on Tue, 6 Sep 2016 22:26:31 +0200 writes: >>>>> >> >>>>> >> > Yesterday, changes to R's development version were committed, >>>>> >> relating >>>>> >> > to arithmetic, logic ('&' and '|') and >>>>> >> > comparison/relational ('<', '==') binary operators >>>>> >> > which in NEWS are described as >>>>> >> >>>>> >> > SIGNIFICANT USER-VISIBLE CHANGES: >>>>> >> >>>>> >> > [.............] >>>>> >> >>>>> >> > ? Arithmetic, logic (?&?, ?|?) and comparison (aka >>>>> >> > ?relational?, e.g., ?<?, ?==?) operations with arrays now >>>>> >> > behave consistently, notably for arrays of length zero. >>>>> >> >>>>> >> > Arithmetic between length-1 arrays and longer non-arrays had >>>>> >> > silently dropped the array attributes and recycled. This >>>>> >> > now gives a warning and will signal an error in the future, >>>>> >> > as it has always for logic and comparison operations in >>>>> >> > these cases (e.g., compare ?matrix(1,1) + 2:3? and >>>>> >> > ?matrix(1,1) < 2:3?). >>>>> >> >>>>> >> > As the above "visually suggests" one could think of the >>>>> changes >>>>> >> > falling mainly two groups, >>>>> >> > 1) <0-extent array> (op) <non-array> >>>>> >> > 2) <1-extent array> (arith) <non-array of length != 1> >>>>> >> >>>>> >> > These changes are partly non-back compatible and may break >>>>> >> > existing code. We believe that the internal consistency >>>>> gained >>>>> >> > from the changes is worth the few places with problems. >>>>> >> >>>>> >> > We expect some package maintainers (10-20, or even more?) need >>>>> >> > to adapt their code. >>>>> >> >>>>> >> > Case '2)' above mainly results in a new warning, e.g., >>>>> >> >>>>> >> >> matrix(1,1) + 1:2 >>>>> >> > [1] 2 3 >>>>> >> > Warning message: >>>>> >> > In matrix(1, 1) + 1:2 : >>>>> >> > dropping dim() of array of length one. Will become ERROR >>>>> >> >> >>>>> >> >>>>> >> > whereas '1)' gives errors in cases the result silently was a >>>>> >> > vector of length zero, or also keeps array (dim & dimnames) in >>>>> >> > cases these were silently dropped. >>>>> >> >>>>> >> > The following is a "heavily" commented R script showing (all >>>> >>>> ?) >>>>> >>>>> >> > the important cases with changes : >>>>> >> >>>>> >> > ------------------------------------------------------------ >>>>> >> ---------------- >>>>> >> >>>>> >> > (m <- cbind(a=1[0], b=2[0])) >>>>> >> > Lm <- m; storage.mode(Lm) <- "logical" >>>>> >> > Im <- m; storage.mode(Im) <- "integer" >>>>> >> >>>>> >> > ## 1. ------------------------- >>>>> >> > try( m & NULL ) # in R <= 3.3.x : >>>>> >> > ## Error in m & NULL : >>>>> >> > ## operations are possible only for numeric, logical or >>>> >>>> complex >>>>> >>>>> >> types >>>>> >> > ## >>>>> >> > ## gives 'Lm' in R >= 3.4.0 >>>>> >> >>>>> >> > ## 2. ------------------------- >>>>> >> > m + 2:3 ## gave numeric(0), now remains matrix identical to m >>>>> >> > Im + 2:3 ## gave integer(0), now remains matrix identical to >>>>> Im >>>>> >> (integer) >>>>> >> >>>>> >> > m > 1 ## gave logical(0), now remains matrix identical to >>>> >>>> Lm >>>>> >>>>> >> (logical) >>>>> >> > m > 0.1[0] ## ditto >>>>> >> > m > NULL ## ditto >>>>> >> >>>>> >> > ## 3. ------------------------- >>>>> >> > mm <- m[,c(1:2,2:1,2)] >>>>> >> > try( m == mm ) ## now gives error "non-conformable arrays", >>>>> >> > ## but gave logical(0) in R <= 3.3.x >>>>> >> >>>>> >> > ## 4. ------------------------- >>>>> >> > str( Im + NULL) ## gave "num", now gives "int" >>>>> >> >>>>> >> > ## 5. ------------------------- >>>>> >> > ## special case for arithmetic w/ length-1 array >>>>> >> > (m1 <- matrix(1,1,1, dimnames=list("Ro","col"))) >>>>> >> > (m2 <- matrix(1,2,1, dimnames=list(c("A","B"),"col"))) >>>>> >> >>>>> >> > m1 + 1:2 # -> 2:3 but now with warning to "become ERROR" >>>>> >> > tools::assertError(m1 & 1:2)# ERR: dims [product 1] do not >>>> >>>> match >>>>> >>>>> the >>>>> >> length of object [2] >>>>> >> > tools::assertError(m1 < 1:2)# ERR: (ditto) >>>>> >> > ## >>>>> >> > ## non-0-length arrays combined with {NULL or double() or ...} >>>>> *fail* >>>>> >> >>>>> >> > ### Length-1 arrays: Arithmetic with |vectors| > 1 treated >>>> >>>> array >>>>> >>>>> >> as scalar >>>>> >> > m1 + NULL # gave numeric(0) in R <= 3.3.x --- still, *but* w/ >>>>> >> warning to "be ERROR" >>>>> >> > try(m1 > NULL) # gave logical(0) in R <= 3.3.x --- an >>>> >>>> *error* >>>>> >>>>> >> now in R >= 3.4.0 >>>>> >> > tools::assertError(m1 & NULL) # gave and gives error >>>>> >> > tools::assertError(m1 | double())# ditto >>>>> >> > ## m2 was slightly different: >>>>> >> > tools::assertError(m2 + NULL) >>>>> >> > tools::assertError(m2 & NULL) >>>>> >> > try(m2 == NULL) ## was logical(0) in R <= 3.3.x; now error as >>>>> above! >>>>> >> >>>>> >> > ------------------------------------------------------------ >>>>> >> ---------------- >>>>> >> >>>>> >> >>>>> >> > Note that in R's own 'nls' sources, there was one case of >>>>> >> > situation '2)' above, i.e. a 1x1-matrix was used as a >>>> >>>> "scalar". >>>>> >>>>> >> >>>>> >> > In such cases, you should explicitly coerce it to a vector, >>>>> >> > either ("self-explainingly") by as.vector(.), or as I did in >>>>> >> > the nls case by c(.) : The latter is much less >>>>> >> > self-explaining, but nicer to read in mathematical formulae, >>>> >>>> and >>>>> >>>>> >> > currently also more efficient because it is a .Primitive. >>>>> >> >>>>> >> > Please use R-devel with your code, and let us know if you see >>>>> >> > effects that seem adverse. >>>>> >> >>>>> >> I've been slightly surprised (or even "frustrated") by the empty >>>>> >> reaction on our R-devel list to this post. >>>>> >> >>>>> >> I would have expected some critique, may be even some praise, >>>>> >> ... in any case some sign people are "thinking along" (as we say >>>>> >> in German). >>>>> >> >>>>> >> In the mean time, I've actually thought along the one case which >>>>> >> is last above: The <op> (binary operation) between a >>>>> >> non-0-length array and a 0-length vector (and NULL which should >>>>> >> be treated like a 0-length vector): >>>>> >> >>>>> >> R <= 3.3.1 *is* quite inconsistent with these: >>>>> >> >>>>> >> >>>>> >> and my proposal above (implemented in R-devel, since Sep.5) >>>>> would >>>>> give an >>>>> >> error for all these, but instead, R really could be more lenient >>>>> here: >>>>> >> A 0-length result is ok, and it should *not* inherit the array >>>>> >> (dim, dimnames), since the array is not of length 0. So instead >>>>> >> of the above [for the very last part only!!], we would aim for >>>>> >> the following. These *all* give an error in current R-devel, >>>>> >> with the exception of 'm1 + NULL' which "only" gives a "bad >>>>> >> warning" : >>>>> >> >>>>> >> ------------------------ >>>>> >> >>>>> >> m1 <- matrix(1,1) >>>>> >> m2 <- matrix(1,2) >>>>> >> >>>>> >> m1 + NULL # numeric(0) in R <= 3.3.x ---> OK ?! >>>>> >> m1 > NULL # logical(0) in R <= 3.3.x ---> OK ?! >>>>> >> try(m1 & NULL) # ERROR in R <= 3.3.x ---> change to >>>>> logical(0) >>>>> ?! >>>>> >> try(m1 | double())# ERROR in R <= 3.3.x ---> change to >>>>> logical(0) >>>>> ?! >>>>> >> ## m2 slightly different: >>>>> >> try(m2 + NULL) # ERROR in R <= 3.3.x ---> change to double(0) >>>> >>>> ?! >>>>> >>>>> >> try(m2 & NULL) # ERROR in R <= 3.3.x ---> change to logical(0) >>>> >>>> ?! >>>>> >>>>> >> m2 == NULL # logical(0) in R <= 3.3.x ---> OK ?! >>>>> >> >>>>> >> ------------------------ >>>>> >> >>>>> >> This would be slightly more back-compatible than the currently >>>>> >> implemented proposal. Everything else I said remains true, and >>>>> >> I'm pretty sure most changes needed in packages would remain to >>>> >>>> be >>>>> >>>>> done. >>>>> >> >>>>> >> Opinions ? >>>>> >> >>>>> >> >>>>> >> >>>>> >> > In some case where R-devel now gives an error but did not >>>>> >> > previously, we could contemplate giving another "warning >>>>> >> > .... 'to become ERROR'" if there was too much breakage, >>>>> though >>>>> >> > I don't expect that. >>>>> >> >>>>> >> >>>>> >> > For the R Core Team, >>>>> >> >>>>> >> > Martin Maechler, >>>>> >> > ETH Zurich >>>>> >> >>>>> >> ______________________________________________ >>>>> >> R-devel at r-project.org mailing list >>>>> >> https://stat.ethz.ch/mailman/listinfo/r-devel >>>>> >> >>>>> >>>>> >>>>> >>>>> > -- >>>>> > Robin Hankin >>>>> > Neutral theorist >>>>> > hankin.robin at gmail.com >>>>> >>>>> > [[alternative HTML version deleted]] >>>>> >>>>> ______________________________________________ >>>>> 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]] >>>> >>>> ______________________________________________ >>>> R-devel at r-project.org mailing list >>>> https://stat.ethz.ch/mailman/listinfo/r-devel >>>> >>> >>> >> >> > > ______________________________________________ > R-devel at r-project.org mailing list > https://stat.ethz.ch/mailman/listinfo/r-devel-- Robin Hankin Neutral theorist hankin.robin at gmail.com
Martin Maechler
2016-Sep-09 06:51 UTC
[Rd] R (development) changes in arith, logic, relop with (0-extent) arrays
Thank you, Gabe and Bill, for taking up the discussion.>>>>> William Dunlap <wdunlap at tibco.com> >>>>> on Thu, 8 Sep 2016 10:45:07 -0700 writes:> Prior to the mid-1990s, S did "length-0 OP length-n -> rep(NA, n)" and it > was changed > to "length-0 OP length-n -> length-0" to avoid lots of problems like > any(x<0) being NA > when length(x)==0. Yes, people could code defensively by putting lots of > if(length(x)==0)... > in their code, but that is tedious and error-prone and creates really ugly > code. Yes, so actually, basically length-0 OP <anything> -> length-0 Now the case of NULL that Bill mentioned. I agree that NULL is not at all the same thing as double(0) or logical(0), *but* there have been quite a few cases, where NULL is the result of operations where "for consistency" double(0) / logical(0) should have been.... and there are the users who use NULL as the equivalent of those, e.g., by initializing a (to be grown, yes, very inefficient!) vector with NULL instead of with say double(0). For these reasons, many operations that expect a "number-like" (includes logical) atomic vector have treated NULL as such... *and* parts of the {arith/logic/relop} OPs have done so already in R "forever". I still would argue that for these OPs, treating NULL as logical(0) {which then may be promoted by the usual rules} is good thing. > Is your suggestion to leave the length-0 OP length-1 case as it is but make > length-0 OP length-two-or-higher an error or warning (akin to the length-2 > OP length-3 case)? That's exactly what one thing the current changes eliminated: arithmetic (only; not logic, or relop) did treat the length-1 case (for arrays!) different from the length-GE-2 case. And I strongly believe that this is very wrong and counter to the predominant recycling rules in (S and) R. > By the way, the all(numeric(0)<0) is TRUE, as is all(numeric()>0), by de > Morgan's rule, but that is not really relevant here. > Bill Dunlap > TIBCO Software > wdunlap tibco.com > On Thu, Sep 8, 2016 at 10:22 AM, Gabriel Becker <gmbecker at ucdavis.edu> > wrote: >> >> >> On Thu, Sep 8, 2016 at 10:05 AM, William Dunlap <wdunlap at tibco.com> wrote: >> >>> Shouldn't binary operators (arithmetic and logical) should throw an error >>> when one operand is NULL (or other type that doesn't make sense)? This is >>> a different case than a zero-length operand of a legitimate type. E.g., >>> any(x < 0) >>> should return FALSE if x is number-like and length(x)==0 but give an >>> error if x is NULL. >>> >> Bill, >> >> That is a good point. I can see the argument for this in the case that the >> non-zero length is 1. I'm not sure which is better though. If we switch >> any() to all(), things get murky. >> >> Mathematically, all(x<0) is TRUE if x is length 0 (as are all(x==0), and >> all(x>0)), but the likelihood of this being a thought-bug on the author's >> part is exceedingly high, imho. So the desirable behavior seems to depend >> on the angle we look at it from. >> >> My personal opinion is that x < y with length(x)==0 should fail if length(y) >> > 1, at least, and I'd be for it being an error even if y is length 1, >> though I do acknowledge this is more likely (though still quite unlikely >> imho) to be the intended behavior. >> >> ~G >> >>> >>> I.e., I think the type check should be done before the length check. >>> >>> >>> Bill Dunlap >>> TIBCO Software >>> wdunlap tibco.com >>> >>> On Thu, Sep 8, 2016 at 8:43 AM, Gabriel Becker <gmbecker at ucdavis.edu> >>> wrote: >>> >>>> Martin, >>>> >>>> Like Robin and Oliver I think this type of edge-case consistency is >>>> important and that it's fantastic that R-core - and you personally - are >>>> willing to tackle some of these "gotcha" behaviors. "Little" stuff like >>>> this really does combine to go a long way to making R better and better. >>>> >>>> I do wonder a bit about the >>>> >>>> x = 1:2 >>>> >>>> y = NULL >>>> >>>> x < y >>>> >>>> case. >>>> >>>> Returning a logical of length 0 is more backwards compatible, but is it >>>> ever what the author actually intended? I have trouble thinking of a case >>>> where that less-than didn't carry an implicit assumption that y was >>>> non-NULL. I can say that in my own code, I've never hit that behavior >>>> in a >>>> case that wasn't an error. >>>> >>>> My vote (unless someone else points out a compelling use for the >>>> behavior) >>>> is for the to throw an error. As a developer, I'd rather things like this >>>> break so the bug in my logic is visible, rather than propagating as the >>>> 0-length logical is &'ed or |'ed with other logical vectors, or used to >>>> subset, or (in the case it should be length 1) passed to if() (if throws >>>> an >>>> error now, but the rest would silently "work"). >>>> >>>> Best, >>>> ~G >>>> >>>> On Thu, Sep 8, 2016 at 3:49 AM, Martin Maechler < >>>> maechler at stat.math.ethz.ch> >>>> wrote: >>>> >>>> > >>>>> robin hankin <hankin.robin at gmail.com> >>>> > >>>>> on Thu, 8 Sep 2016 10:05:21 +1200 writes: >>>> > >>>> > > Martin I'd like to make a comment; I think that R's >>>> > > behaviour on 'edge' cases like this is an important thing >>>> > > and it's great that you are working on it. >>>> > >>>> > > I make heavy use of zero-extent arrays, chiefly because >>>> > > the dimnames are an efficient and logical way to keep >>>> > > track of certain types of information. >>>> > >>>> > > If I have, for example, >>>> > >>>> > > a <- array(0,c(2,0,2)) >>>> > > dimnames(a) <- list(name=c('Mike','Kevin'), >>>> > NULL,item=c("hat","scarf")) >>>> > >>>> > >>>> > > Then in R-3.3.1, 70800 I get >>>> > >>>> > a> 0 >>>> > > logical(0) >>>> > >> >>>> > >>>> > > But in 71219 I get >>>> > >>>> > a> 0 >>>> > > , , item = hat >>>> > >>>> > >>>> > > name >>>> > > Mike >>>> > > Kevin >>>> > >>>> > > , , item = scarf >>>> > >>>> > >>>> > > name >>>> > > Mike >>>> > > Kevin >>>> > >>>> > > (which is an empty logical array that holds the names of the >>>> people >>>> > and >>>> > > their clothes). I find the behaviour of 71219 very much >>>> preferable >>>> > because >>>> > > there is no reason to discard the information in the dimnames. >>>> > >>>> > Thanks a lot, Robin, (and Oliver) ! >>>> > >>>> > Yes, the above is such a case where the new behavior makes much sense. >>>> > And this behavior remains identical after the 71222 amendment. >>>> > >>>> > Martin >>>> > >>>> > > Best wishes >>>> > > Robin >>>> > >>>> > >>>> > >>>> > >>>> > > On Wed, Sep 7, 2016 at 9:49 PM, Martin Maechler < >>>> > maechler at stat.math.ethz.ch> >>>> > > wrote: >>>> > >>>> > >> >>>>> Martin Maechler <maechler at stat.math.ethz.ch> >>>> > >> >>>>> on Tue, 6 Sep 2016 22:26:31 +0200 writes: >>>> > >> >>>> > >> > Yesterday, changes to R's development version were committed, >>>> > >> relating >>>> > >> > to arithmetic, logic ('&' and '|') and >>>> > >> > comparison/relational ('<', '==') binary operators >>>> > >> > which in NEWS are described as >>>> > >> >>>> > >> > SIGNIFICANT USER-VISIBLE CHANGES: >>>> > >> >>>> > >> > [.............] >>>> > >> >>>> > >> > ? Arithmetic, logic (?&?, ?|?) and comparison (aka >>>> > >> > ?relational?, e.g., ?<?, ?==?) operations with arrays now >>>> > >> > behave consistently, notably for arrays of length zero. >>>> > >> >>>> > >> > Arithmetic between length-1 arrays and longer non-arrays had >>>> > >> > silently dropped the array attributes and recycled. This >>>> > >> > now gives a warning and will signal an error in the future, >>>> > >> > as it has always for logic and comparison operations in >>>> > >> > these cases (e.g., compare ?matrix(1,1) + 2:3? and >>>> > >> > ?matrix(1,1) < 2:3?). >>>> > >> >>>> > >> > As the above "visually suggests" one could think of the >>>> changes >>>> > >> > falling mainly two groups, >>>> > >> > 1) <0-extent array> (op) <non-array> >>>> > >> > 2) <1-extent array> (arith) <non-array of length != 1> >>>> > >> >>>> > >> > These changes are partly non-back compatible and may break >>>> > >> > existing code. We believe that the internal consistency >>>> gained >>>> > >> > from the changes is worth the few places with problems. >>>> > >> >>>> > >> > We expect some package maintainers (10-20, or even more?) need >>>> > >> > to adapt their code. >>>> > >> >>>> > >> > Case '2)' above mainly results in a new warning, e.g., >>>> > >> >>>> > >> >> matrix(1,1) + 1:2 >>>> > >> > [1] 2 3 >>>> > >> > Warning message: >>>> > >> > In matrix(1, 1) + 1:2 : >>>> > >> > dropping dim() of array of length one. Will become ERROR >>>> > >> >> >>>> > >> >>>> > >> > whereas '1)' gives errors in cases the result silently was a >>>> > >> > vector of length zero, or also keeps array (dim & dimnames) in >>>> > >> > cases these were silently dropped. >>>> > >> >>>> > >> > The following is a "heavily" commented R script showing (all >>>> ?) >>>> > >> > the important cases with changes : >>>> > >> >>>> > >> > ------------------------------------------------------------ >>>> > >> ---------------- >>>> > >> >>>> > >> > (m <- cbind(a=1[0], b=2[0])) >>>> > >> > Lm <- m; storage.mode(Lm) <- "logical" >>>> > >> > Im <- m; storage.mode(Im) <- "integer" >>>> > >> >>>> > >> > ## 1. ------------------------- >>>> > >> > try( m & NULL ) # in R <= 3.3.x : >>>> > >> > ## Error in m & NULL : >>>> > >> > ## operations are possible only for numeric, logical or >>>> complex >>>> > >> types >>>> > >> > ## >>>> > >> > ## gives 'Lm' in R >= 3.4.0 >>>> > >> >>>> > >> > ## 2. ------------------------- >>>> > >> > m + 2:3 ## gave numeric(0), now remains matrix identical to m >>>> > >> > Im + 2:3 ## gave integer(0), now remains matrix identical to >>>> Im >>>> > >> (integer) >>>> > >> >>>> > >> > m > 1 ## gave logical(0), now remains matrix identical >>>> to Lm >>>> > >> (logical) >>>> > >> > m > 0.1[0] ## ditto >>>> > >> > m > NULL ## ditto >>>> > >> >>>> > >> > ## 3. ------------------------- >>>> > >> > mm <- m[,c(1:2,2:1,2)] >>>> > >> > try( m == mm ) ## now gives error "non-conformable arrays", >>>> > >> > ## but gave logical(0) in R <= 3.3.x >>>> > >> >>>> > >> > ## 4. ------------------------- >>>> > >> > str( Im + NULL) ## gave "num", now gives "int" >>>> > >> >>>> > >> > ## 5. ------------------------- >>>> > >> > ## special case for arithmetic w/ length-1 array >>>> > >> > (m1 <- matrix(1,1,1, dimnames=list("Ro","col"))) >>>> > >> > (m2 <- matrix(1,2,1, dimnames=list(c("A","B"),"col"))) >>>> > >> >>>> > >> > m1 + 1:2 # -> 2:3 but now with warning to "become ERROR" >>>> > >> > tools::assertError(m1 & 1:2)# ERR: dims [product 1] do not >>>> match >>>> > the >>>> > >> length of object [2] >>>> > >> > tools::assertError(m1 < 1:2)# ERR: (ditto) >>>> > >> > ## >>>> > >> > ## non-0-length arrays combined with {NULL or double() or ...} >>>> > *fail* >>>> > >> >>>> > >> > ### Length-1 arrays: Arithmetic with |vectors| > 1 treated >>>> array >>>> > >> as scalar >>>> > >> > m1 + NULL # gave numeric(0) in R <= 3.3.x --- still, *but* w/ >>>> > >> warning to "be ERROR" >>>> > >> > try(m1 > NULL) # gave logical(0) in R <= 3.3.x --- an >>>> *error* >>>> > >> now in R >= 3.4.0 >>>> > >> > tools::assertError(m1 & NULL) # gave and gives error >>>> > >> > tools::assertError(m1 | double())# ditto >>>> > >> > ## m2 was slightly different: >>>> > >> > tools::assertError(m2 + NULL) >>>> > >> > tools::assertError(m2 & NULL) >>>> > >> > try(m2 == NULL) ## was logical(0) in R <= 3.3.x; now error as >>>> > above! >>>> > >> >>>> > >> > ------------------------------------------------------------ >>>> > >> ---------------- >>>> > >> >>>> > >> >>>> > >> > Note that in R's own 'nls' sources, there was one case of >>>> > >> > situation '2)' above, i.e. a 1x1-matrix was used as a >>>> "scalar". >>>> > >> >>>> > >> > In such cases, you should explicitly coerce it to a vector, >>>> > >> > either ("self-explainingly") by as.vector(.), or as I did in >>>> > >> > the nls case by c(.) : The latter is much less >>>> > >> > self-explaining, but nicer to read in mathematical formulae, >>>> and >>>> > >> > currently also more efficient because it is a .Primitive. >>>> > >> >>>> > >> > Please use R-devel with your code, and let us know if you see >>>> > >> > effects that seem adverse. >>>> > >> >>>> > >> I've been slightly surprised (or even "frustrated") by the empty >>>> > >> reaction on our R-devel list to this post. >>>> > >> >>>> > >> I would have expected some critique, may be even some praise, >>>> > >> ... in any case some sign people are "thinking along" (as we say >>>> > >> in German). >>>> > >> >>>> > >> In the mean time, I've actually thought along the one case which >>>> > >> is last above: The <op> (binary operation) between a >>>> > >> non-0-length array and a 0-length vector (and NULL which should >>>> > >> be treated like a 0-length vector): >>>> > >> >>>> > >> R <= 3.3.1 *is* quite inconsistent with these: >>>> > >> >>>> > >> >>>> > >> and my proposal above (implemented in R-devel, since Sep.5) >>>> would >>>> > give an >>>> > >> error for all these, but instead, R really could be more lenient >>>> > here: >>>> > >> A 0-length result is ok, and it should *not* inherit the array >>>> > >> (dim, dimnames), since the array is not of length 0. So instead >>>> > >> of the above [for the very last part only!!], we would aim for >>>> > >> the following. These *all* give an error in current R-devel, >>>> > >> with the exception of 'm1 + NULL' which "only" gives a "bad >>>> > >> warning" : >>>> > >> >>>> > >> ------------------------ >>>> > >> >>>> > >> m1 <- matrix(1,1) >>>> > >> m2 <- matrix(1,2) >>>> > >> >>>> > >> m1 + NULL # numeric(0) in R <= 3.3.x ---> OK ?! >>>> > >> m1 > NULL # logical(0) in R <= 3.3.x ---> OK ?! >>>> > >> try(m1 & NULL) # ERROR in R <= 3.3.x ---> change to >>>> logical(0) >>>> > ?! >>>> > >> try(m1 | double())# ERROR in R <= 3.3.x ---> change to >>>> logical(0) >>>> > ?! >>>> > >> ## m2 slightly different: >>>> > >> try(m2 + NULL) # ERROR in R <= 3.3.x ---> change to double(0) >>>> ?! >>>> > >> try(m2 & NULL) # ERROR in R <= 3.3.x ---> change to >>>> logical(0) ?! >>>> > >> m2 == NULL # logical(0) in R <= 3.3.x ---> OK ?! >>>> > >> >>>> > >> ------------------------ >>>> > >> >>>> > >> This would be slightly more back-compatible than the currently >>>> > >> implemented proposal. Everything else I said remains true, and >>>> > >> I'm pretty sure most changes needed in packages would remain to >>>> be >>>> > done. >>>> > >> >>>> > >> Opinions ? >>>> > >> >>>> > >> >>>> > >> >>>> > >> > In some case where R-devel now gives an error but did not >>>> > >> > previously, we could contemplate giving another "warning >>>> > >> > .... 'to become ERROR'" if there was too much breakage, >>>> though >>>> > >> > I don't expect that. >>>> > >> >>>> > >> >>>> > >> > For the R Core Team, >>>> > >> >>>> > >> > Martin Maechler, >>>> > >> > ETH Zurich >>>> > >> >>>> > >> ______________________________________________ >>>> > >> R-devel at r-project.org mailing list >>>> > >> https://stat.ethz.ch/mailman/listinfo/r-devel >>>> > >> >>>> > >>>> > >>>> > >>>> > > -- >>>> > > Robin Hankin >>>> > > Neutral theorist >>>> > > hankin.robin at gmail.com >>>> > >>>> > > [[alternative HTML version deleted]] >>>> > >>>> > ______________________________________________ >>>> > 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]] >>>> >>>> ______________________________________________ >>>> 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]]
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