Re: [Rd] R (development) changes in arith, logic, relop with (0-extent) arrays

[Hervé Pagès]

Hi,

On 09/12/2016 08:21 AM, Martin Maechler wrote:

Radford Neal 
on Fri, 9 Sep 2016 10:29:14 -0400 writes:


>> Radford Nea:
>> > So it may make more sense to move towards consistency in the
>> > permissive direction, rather than the restrictive direction.
>>
>> > That would mean allowing matrix(1,1,1) < (1:2), and maybe also things
>> > like matrix(1,2,2)+(1:8).
>>
>> Martin Maechler:
>> That is an interesting idea.  Yes, in my view that would
>> definitely also have to allow the latter, by the above argument
>> of not treating the dim/dimnames attributes special.  For
>> non-arrays length-1 is not treated much special apart from the
>> fact that length-1 can always be recycled (without warning).

> I think one could argue for allowing matrix(1,1,1)+(1:8) but not
> matrix(1,2,2)+(1:8).  Length-1 vectors certainly are special in some
> circumstances, being R's only way of representing a scalar.  For
> instance, if (c(T,F)) gives a warning.

well, the if(.)  situation is very special and does not weigh
much for me, here.

> This really goes back to what I think may have been a basic mistake in
> the design of S, in deciding that everything is a vector, then halfway
> modifying this with dim attributes, but it's too late to totally undo
> that (though allowing a 0-length dim attribute to explicitly mark a
> length-1 vector as a scalar might help).

(yes; I think there are also other ideas of adding true small
 scalars to R... I am not familiar with those, and in any case
 that should be a completely different thread and not be
 discussed in this one)

>> > And I think there would be some significant problems. In addition to
>> > the 10-20+ packages that Martin expects to break, there could be quite
>> > a bit of user code that would no longer work - scripts for analysing
>> > data sets that used to work, but now don't with the latest version.
>>
>> That's not true (at least for the cases above): They would give
>> a strong warning

> But isn't the intent to make it an error later?  So I assume we're
> debating making it an error, not just a warning.

Yes, that's correct.
But if we have a longish deprecation period (i.e. where there's
only a warning) all important code should have been adapted
before it turns to an error
 (( unless for those people who are careless enough to "graciously"
use something like suppressWarnings(...) in too many places )).


Any reason for not using the formal deprecation mechanism (i.e.
.Deprecated()) for this? The advantage being that 'R CMD check'
reports deprecation warnings and not ordinary warnings, IIRC. It
won't help (and won't hurt either) in the case of packages using
suppressWarnings(...) but maybe suppressWarnings() shouldn't suppress
deprecation warnings, at least be default.

Cheers,
H.



> (Though I'm
> generally opposed to such warnings anyway, unless they could somehow
> be restricted to come up only for interactive uses, not from deep in a
> program the user didn't write, making them totally mysterious...)

>> *and* the  logic and relop versions of this, e.g.,
>> matrix(TRUE,1) | c(TRUE,FALSE) ;  matrix(1,1) > 1:2,
>> have always been an  error; so nothing would break there.

> Yes, that wouldn't change the behaviour of old code, but if we're
> aiming for consistency, it might make sense to get rid of that error,
> allowing code like sum(a%*%b rather than forcing the programmer to write sum(c(a%*%b)> Of course; that *was* the reason the very special treatment for 
arithmetic
>> length-1 arrays had been introduced.  It is convenient.
>>
>> However, *some* of the conveniences in S (and hence R) functions
>> have been dangerous {and much more used, hence close to
>> impossible to abolish, e.g., sample(x) when x  is numeric of 

Re: [Rd] R (development) changes in arith, logic, relop with (0-extent) arrays

[Gabriel Becker]

On Mon, Sep 12, 2016 at 9:51 AM, Radford Neal 
wrote:

> > > But isn't the intent to make it an error later?  So I assume we're
> > > debating making it an error, not just a warning.
> >
> > Yes, that's correct.
> > But if we have a longish deprecation period (i.e. where there's
> > only a warning) all important code should have been adapted
> > before it turns to an error
>
> That might be true for continuously-used code.  But for old scripts
> for analysing some dataset that someone decides to run again five
> years from now, they will be reduced to trying to guess which version
> of R they ran under originally,


In the general case this is true of any packages they use anyway, though.
And if you go back far enough old package versions can't even be installed
for current versions of R.

Results are always contingent on the software, including versions, used to
generate them imho. There are ways to try to address this, but they can be
painful and generally require extra work the author of any 5 year old
script you have in your hands now likely didn't do.


> or if they now want to use newer
> features, to doing a binary search for the most recent version of R
> for which they still work, or of course going through the script
> trying to find the problem.
>

Now you're talking not about running a script, though, but of maintaining
and developing it. I know from personal experience how painful developing
on top of legacy code can be, but nonetheless sometimes It needs to be
maintained and updated.

If you really want absolute safety, that is (more or less) possible, but it
means staying in an old version of R with old package versions. I don't
think the expectation of being guaranteed to be able to use new features
and unmodified legacy code at the same time is reasonable. It's great what
that does happen, but it's a bonus imho, not a requirement.

Best,
~G




>
> This wouldn't be a disaster, but I'm not seeing the magnitude of
> benefit that would justify imposing this burden on users.  A language
> specification shouldn't really be changing all the time for no
> particular reason.
>
>Radford Neal
>
> __
> R-devel@r-project.org mailing list
> https://stat.ethz.ch/mailman/listinfo/r-devel
>



-- 
Gabriel Becker, PhD
Associate Scientist (Bioinformatics)
Genentech Research

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Re: [Rd] R (development) changes in arith, logic, relop with (0-extent) arrays

[Radford Neal]

> > But isn't the intent to make it an error later?  So I assume we're
> > debating making it an error, not just a warning.  
> 
> Yes, that's correct.
> But if we have a longish deprecation period (i.e. where there's
> only a warning) all important code should have been adapted
> before it turns to an error 

That might be true for continuously-used code.  But for old scripts
for analysing some dataset that someone decides to run again five
years from now, they will be reduced to trying to guess which version
of R they ran under originally, or if they now want to use newer
features, to doing a binary search for the most recent version of R
for which they still work, or of course going through the script
trying to find the problem.

This wouldn't be a disaster, but I'm not seeing the magnitude of
benefit that would justify imposing this burden on users.  A language
specification shouldn't really be changing all the time for no
particular reason.

   Radford Neal

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Re: [Rd] R (development) changes in arith, logic, relop with (0-extent) arrays

[Martin Maechler]

> Radford Neal 
> on Fri, 9 Sep 2016 10:29:14 -0400 writes:

>> Radford Nea:
>> > So it may make more sense to move towards consistency in the
>> > permissive direction, rather than the restrictive direction.
>> 
>> > That would mean allowing matrix(1,1,1) < (1:2), and maybe also things
>> > like matrix(1,2,2)+(1:8).
>> 
>> Martin Maechler:
>> That is an interesting idea.  Yes, in my view that would
>> definitely also have to allow the latter, by the above argument
>> of not treating the dim/dimnames attributes special.  For
>> non-arrays length-1 is not treated much special apart from the
>> fact that length-1 can always be recycled (without warning).

> I think one could argue for allowing matrix(1,1,1)+(1:8) but not
> matrix(1,2,2)+(1:8).  Length-1 vectors certainly are special in some
> circumstances, being R's only way of representing a scalar.  For
> instance, if (c(T,F)) gives a warning.

well, the if(.)  situation is very special and does not weigh
much for me, here.

> This really goes back to what I think may have been a basic mistake in
> the design of S, in deciding that everything is a vector, then halfway
> modifying this with dim attributes, but it's too late to totally undo
> that (though allowing a 0-length dim attribute to explicitly mark a
> length-1 vector as a scalar might help).

(yes; I think there are also other ideas of adding true small
 scalars to R... I am not familiar with those, and in any case
 that should be a completely different thread and not be
 discussed in this one)

>> > And I think there would be some significant problems. In addition to
>> > the 10-20+ packages that Martin expects to break, there could be quite
>> > a bit of user code that would no longer work - scripts for analysing
>> > data sets that used to work, but now don't with the latest version.
>> 
>> That's not true (at least for the cases above): They would give
>> a strong warning

> But isn't the intent to make it an error later?  So I assume we're
> debating making it an error, not just a warning.  

Yes, that's correct.
But if we have a longish deprecation period (i.e. where there's
only a warning) all important code should have been adapted
before it turns to an error 
 (( unless for those people who are careless enough to "graciously"
use something like suppressWarnings(...) in too many places )).

> (Though I'm
> generally opposed to such warnings anyway, unless they could somehow
> be restricted to come up only for interactive uses, not from deep in a
> program the user didn't write, making them totally mysterious...)

>> *and* the  logic and relop versions of this, e.g.,
>> matrix(TRUE,1) | c(TRUE,FALSE) ;  matrix(1,1) > 1:2,
>> have always been an  error; so nothing would break there.

> Yes, that wouldn't change the behaviour of old code, but if we're
> aiming for consistency, it might make sense to get rid of that error,
> allowing code like sum(a%*%b rather than forcing the programmer to write sum(c(a%*%b)> Of course; that *was* the reason the very special treatment for 
arithmetic
>> length-1 arrays had been introduced.  It is convenient.
>> 
>> However, *some* of the conveniences in S (and hence R) functions
>> have been dangerous {and much more used, hence close to
>> impossible to abolish, e.g., sample(x) when x  is numeric of length 1,

> There's a difference between these two.  Giving an error when using a
> 1x1 matrix as a scalar may detect some programming bugs, but not
> giving an error doesn't introduce a bug.  Whereas sample(2:n) behaving
> differently when n is 2 than when n is greater than 2 is itself a bug,
> that the programmer has to consciously avoid by being aware of the quirk.

> Radford Neal

Re: [Rd] R (development) changes in arith, logic, relop with (0-extent) arrays

[Gabriel Becker]

Martin et al.,

I seem to be in the minority here, so I won't belabor the point too much,
but one last response inline:

On Thu, Sep 8, 2016 at 11:51 PM, Martin Maechler  wrote:

> Thank you, Gabe and Bill,
>
> for taking up the discussion.
>
> > William Dunlap 
> > 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   -> 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.
>

In my view, the recycling rules apply first and foremost to pairs of
vectors of lengths n,m >=1. And they can be semantically explained in that
case very easily: "the shorter, non-zero-length vector is rep'ed out to be
the length of the longer vector and then (generally) an element wise
operation takes place". The zero-length behavior already does not adhere to
this definition, as it would be impossible to do in the case of a
zero-length vector and a nonzero-length vector.

So the zero-length recycling behavior is already special-cased as I
understand it. In light of that, it seems that it would be allowable to
have different behavior based on the length of the other vector.
Furthermore, while I acknowledge the usefulness of the

x = numeric()

x <  5


case (i.e., the other vector is length 1), I can't come up with any use of,
e.g.,

y  = numeric()
y < 3:5


That I can make any sense of other than as a violation of implicit
assumptions by the coder about the length of y.

Thus, I still think that should at *least* warn, preferably (imho) give an
error.

Best,
~G


-- 
Gabriel Becker, PhD
Associate Scientist (Bioinformatics)
Genentech Research

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Re: [Rd] R (development) changes in arith, logic, relop with (0-extent) arrays

[Paul Gilbert]

On 09/08/2016 05:06 PM, robin hankin wrote:

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 fear you are thinking of this as an end user, rather than as a package 
developer. Warnings are for end users, when they do something they 
possibly should be warned about. A package really should not generate 
warnings unless they are for end user consumption. In package 
development I treat warnings the same way I treat errors: build fails, 
program around it. So what you call a compromise is no compromise at all 
as far as I am concerned.


But perhaps there is a use for an end user version, maybe All() or ALL() 
that issues an error or warning. There are a lot of functions and 
operators in R that could warn about mistakes that a user may be making.


Paul



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  wrote:



On 09/08/2016 01:22 PM, Gabriel Becker wrote:


On Thu, Sep 8, 2016 at 10:05 AM, William Dunlap  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 
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 <
maech...@stat.math.ethz.ch>
wrote:


robin hankin 
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
   

Re: [Rd] R (development) changes in arith, logic, relop with (0-extent) arrays

[Radford Neal]

> Radford Nea:
> > So it may make more sense to move towards consistency in the
> > permissive direction, rather than the restrictive direction.
> 
> > That would mean allowing matrix(1,1,1) < (1:2), and maybe also things
> > like matrix(1,2,2)+(1:8).
> 
> Martin Maechler:
> That is an interesting idea.  Yes, in my view that would
> definitely also have to allow the latter, by the above argument
> of not treating the dim/dimnames attributes special.  For
> non-arrays length-1 is not treated much special apart from the
> fact that length-1 can always be recycled (without warning).

I think one could argue for allowing matrix(1,1,1)+(1:8) but not
matrix(1,2,2)+(1:8).  Length-1 vectors certainly are special in some
circumstances, being R's only way of representing a scalar.  For
instance, if (c(T,F)) gives a warning.

This really goes back to what I think may have been a basic mistake in
the design of S, in deciding that everything is a vector, then halfway
modifying this with dim attributes, but it's too late to totally undo
that (though allowing a 0-length dim attribute to explicitly mark a
length-1 vector as a scalar might help).

> > And I think there would be some significant problems. In addition to
> > the 10-20+ packages that Martin expects to break, there could be quite
> > a bit of user code that would no longer work - scripts for analysing
> > data sets that used to work, but now don't with the latest version.
> 
> That's not true (at least for the cases above): They would give
> a strong warning

But isn't the intent to make it an error later?  So I assume we're
debating making it an error, not just a warning.  (Though I'm
generally opposed to such warnings anyway, unless they could somehow
be restricted to come up only for interactive uses, not from deep in a
program the user didn't write, making them totally mysterious...)

> *and* the  logic and relop versions of this, e.g.,
>matrix(TRUE,1) | c(TRUE,FALSE) ;  matrix(1,1) > 1:2,
> have always been an  error; so nothing would break there.

Yes, that wouldn't change the behaviour of old code, but if we're
aiming for consistencey, it might make sense to get rid of that error,
allowing code like sum(a%*%b Of course; that *was* the reason the very special treatment for arithmetic
> length-1 arrays had been introduced.  It is convenient.
> 
> However, *some* of the conveniences in S (and hence R) functions
> have been dangerous {and much more used, hence close to
> impossible to abolish, e.g., sample(x) when x  is numeric of length 1,

There's a difference between these two.  Giving an error when using a
1x1 matrix as a scalar may detect some programming bugs, but not
giving an error doesn't introduce a bug.  Whereas sample(2:n) behaving
differently when n is 2 than when n is greater than 2 is itself a bug,
that the programmer has to consciously avoid by being aware of the quirk.

   Radford Neal

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Re: [Rd] R (development) changes in arith, logic, relop with (0-extent) arrays

[Martin Maechler]

> Radford Neal 
> on Thu, 8 Sep 2016 17:11:18 -0400 writes:

> Regarding Martin Maechler's proposal:
> 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

> For example, matrix(1,1,1) + (1:2) would give a warning/error.

> I think this might be a mistake.

> The potential benefits of this would be detection of some programming
> errors, and increased consistency.  The downsides are breaking
> existing working programs, and decreased consistency.

> Regarding consistency, the overall R philosophy is that attaching an
> attribute to a vector doesn't change what you can do with it, or what
> the result is, except that the result (often) gets the attributes
> carried forward.  By this logic, adding a 'dim' attribute shouldn't
> stop you from doing arithmetic (or comparisons) that you otherwise
> could.

Thank you, Radford, for joining in.
The above is a good line of reasoning.

> But maybe 'dim' attributes are special?  Well, they are in some
> circumstances, and have to be when they are intended to change the
> behaviour, such as when a matrix is used as an index with [.

indeed.

> But in many cases at present, 'dim' attributes DON'T stop you from
> treating the object as a plain vector - for example, one is allowed 
> to do matrix(1:4,2,2)[3], and a<-numeric(10); a[2:5]<-matrix(1,2,2).

agreed.

> So it may make more sense to move towards consistency in the
> permissive direction, rather than the restrictive direction.

> That would mean allowing matrix(1,1,1) < (1:2), and maybe also things
> like matrix(1,2,2)+(1:8).

That is an interesting idea.  Yes, in my view that would
definitely also have to allow the latter, by the above argument
of not treating the dim/dimnames attributes special.  For
non-arrays length-1 is not treated much special apart from the
fact that length-1 can always be recycled (without warning).


> Obviously, a change that removes error conditions is much less likely
> to produce backwards-compatibility problems than a change that gives
> errors for previously-allowed operations.

Of course that is true... and that has also been the reason for
my amendment

> And I think there would be some significant problems. In addition to
> the 10-20+ packages that Martin expects to break, there could be quite
> a bit of user code that would no longer work - scripts for analysing
> data sets that used to work, but now don't with the latest version.

That's not true (at least for the cases above): They would give
a strong warning, "strong" because it is

   > 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
   > 

*and* the  logic and relop versions of this, e.g.,
   matrix(TRUE,1) | c(TRUE,FALSE) ;  matrix(1,1) > 1:2,
have always been an  error; so nothing would break there.


> There are reasons to expect such problems.  Some operations such as
> vector dot products using %*% produce results that are always scalar,
> but are formed as 1x1 matrices.

Of course; that *was* the reason the very special treatment for arithmetic
length-1 arrays had been introduced.  It is convenient.

However, *some* of the conveniences in S (and hence R) functions
have been dangerous {and much more used, hence close to
impossible to abolish, e.g., sample(x) when x  is numeric of length 1,
and several others, you'll find in the "R Inferno"}, or at least
quirky for *programming* with R (as opposed to pure interactive use).

> One can anticipate that many people
> have not been getting rid of the 'dim' attribute in such cases, when
> doing so hasn't been necessary in the past.

If it remains at 10-20 CRAN packages (out of 9000), each with
just very few instances, that would indicate I think not so wide
spread use.
Note that they only did not have to get rid of the dim() in the
length-1 case (and only for arithmetic): as soon as they had
another dimension, they would have got an error.

Still, I agree about the validity of your line of thought, and
that in order to get consistency we also could go into the
direction of being more permissive rather than restrictive.

I'm interested to hear other opinions notably as in recent years,
some famous R teachers have typically critized R are as being
not strict enough ...

> Regarding the 0-length vector issue, I agree with other posters that
> after a<-numeric(0), is has to be allowable to write a<1.  To not
> allow this would be highly destructive of code reliability.  And for
> similar reason, after a<-c(), a<1 needs to be allowed, which means
> NULL<1 should be allowed (giving logical(0)), since 

Re: [Rd] R (development) changes in arith, logic, relop with (0-extent) arrays

[Martin Maechler]

Thank you, Gabe and Bill,

for taking up the discussion.

> William Dunlap 
> 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   -> 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 
> wrote:

>> 
>> 
>> On Thu, Sep 8, 2016 at 10:05 AM, William Dunlap  
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 
>>> 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 

Re: [Rd] R (development) changes in arith, logic, relop with (0-extent) arrays

[Radford Neal]

Regarding Martin Maechler's proposal:

   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

For example, matrix(1,1,1) + (1:2) would give a warning/error.

I think this might be a mistake.

The potential benefits of this would be detection of some programming
errors, and increased consistency.  The downsides are breaking
existing working programs, and decreased consistency.

Regarding consistency, the overall R philosophy is that attaching an
attribute to a vector doesn't change what you can do with it, or what
the result is, except that the result (often) gets the attributes
carried forward.  By this logic, adding a 'dim' attribute shouldn't
stop you from doing arithmetic (or comparisons) that you otherwise
could.

But maybe 'dim' attributes are special?  Well, they are in some
circumstances, and have to be when they are intended to change the
behaviour, such as when a matrix is used as an index with [.

But in many cases at present, 'dim' attributes DON'T stop you from
treating the object as a plain vector - for example, one is allowed 
to do matrix(1:4,2,2)[3], and a<-numeric(10); a[2:5]<-matrix(1,2,2).

So it may make more sense to move towards consistency in the
permissive direction, rather than the restrictive direction.  That
would mean allowing matrix(1,1,1)<(1:2), and maybe also things
like matrix(1,2,2)+(1:8).

Obviously, a change that removes error conditions is much less likely
to produce backwards-compatibility problems than a change that gives
errors for previously-allowed operations.

And I think there would be some significant problems. In addition to
the 10-20+ packages that Martin expects to break, there could be quite
a bit of user code that would no longer work - scripts for analysing
data sets that used to work, but now don't with the latest version.

There are reasons to expect such problems.  Some operations such as
vector dot products using %*% produce results that are always scalar,
but are formed as 1x1 matrices.  One can anticipate that many people
have not been getting rid of the 'dim' attribute in such cases, when
doing so hasn't been necessary in the past.

Regarding the 0-length vector issue, I agree with other posters that
after a<-numeric(0), is has to be allowable to write a<1.  To not
allow this would be highly destructive of code reliability.  And for
similar reason, after a<-c(), a<1 needs to be allowed, which means
NULL<1 should be allowed (giving logical(0)), since c() is NULL.

   Radford Neal

__
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel

Re: [Rd] R (development) changes in arith, logic, relop with (0-extent) arrays

[robin hankin]

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  wrote:
>
>
> On 09/08/2016 01:22 PM, Gabriel Becker wrote:
>>
>> On Thu, Sep 8, 2016 at 10:05 AM, William Dunlap  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 
>>> 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 <
 maech...@stat.math.ethz.ch>
 wrote:

>> robin hankin 
>> 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
>

Re: [Rd] R (development) changes in arith, logic, relop with (0-extent) arrays

[Paul Gilbert]

On 09/08/2016 01:22 PM, Gabriel Becker wrote:

On Thu, Sep 8, 2016 at 10:05 AM, William Dunlap  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 
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 <
maech...@stat.math.ethz.ch>
wrote:


robin hankin 
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 <
maech...@stat.math.ethz.ch>
> wrote:

>> > Martin Maechler 
>> > 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 

Re: [Rd] R (development) changes in arith, logic, relop with (0-extent) arrays

[William Dunlap via R-devel]

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 
wrote:

>
>
> On Thu, Sep 8, 2016 at 10:05 AM, William Dunlap  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 
>> 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 <
>>> maech...@stat.math.ethz.ch>
>>> wrote:
>>>
>>> > > robin hankin 
>>> > > 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 

Re: [Rd] R (development) changes in arith, logic, relop with (0-extent) arrays

[Gabriel Becker]

On Thu, Sep 8, 2016 at 10:05 AM, William Dunlap  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 
> 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 <
>> maech...@stat.math.ethz.ch>
>> wrote:
>>
>> > > robin hankin 
>> > > 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 <
>> > maech...@stat.math.ethz.ch>
>> > > wrote:
>> >
>> > >> > Martin Maechler 
>> > >> > 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.
>> >  

Re: [Rd] R (development) changes in arith, logic, relop with (0-extent) arrays

[William Dunlap via R-devel]

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.

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  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 <
> maech...@stat.math.ethz.ch>
> wrote:
>
> > > robin hankin 
> > > 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 <
> > maech...@stat.math.ethz.ch>
> > > wrote:
> >
> > >> > Martin Maechler 
> > >> > 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) 
> > >> > 2) <1-extent array>  (arith)  
> > >>
> > >> > 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
> > >> > 

Re: [Rd] R (development) changes in arith, logic, relop with (0-extent) arrays

[Gabriel Becker]

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 
wrote:

> > robin hankin 
> > 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 <
> maech...@stat.math.ethz.ch>
> > wrote:
>
> >> > Martin Maechler 
> >> > 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) 
> >> > 2) <1-extent array>  (arith)  
> >>
> >> > 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]))

Re: [Rd] R (development) changes in arith, logic, relop with (0-extent) arrays

[Martin Maechler]

> robin hankin 
> 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 

> wrote:

>> > Martin Maechler 
>> > 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) 
>> > 2) <1-extent array>  (arith)  
>> 
>> > 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 

Re: [Rd] R (development) changes in arith, logic, relop with (0-extent) arrays

[Oliver Keyes]

+1. Very grateful; more consistency is always great :)

On Wednesday, 7 September 2016, robin hankin  wrote:

> 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.
>
>
> Best wishes
>
> Robin
>
>
>
>
> On Wed, Sep 7, 2016 at 9:49 PM, Martin Maechler <
> maech...@stat.math.ethz.ch >
> wrote:
>
> > > Martin Maechler >
> > > 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) 
> > > 2) <1-extent array>  (arith)  
> >
> > > 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*
> >
> > > ### 

Re: [Rd] R (development) changes in arith, logic, relop with (0-extent) arrays

[robin hankin]

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.


Best wishes

Robin




On Wed, Sep 7, 2016 at 9:49 PM, Martin Maechler 
wrote:

> > Martin Maechler 
> > 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) 
> > 2) <1-extent array>  (arith)  
>
> > 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 + 

Re: [Rd] R (development) changes in arith, logic, relop with (0-extent) arrays

[Martin Maechler]

> Martin Maechler 
> on Wed, 7 Sep 2016 11:49:11 +0200 writes:

> Martin Maechler 
> 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) 
>> 2) <1-extent array>  (arith)  

>> 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 

Re: [Rd] R (development) changes in arith, logic relop with 0-extent arrays

[Therneau, Terry M., Ph.D.]

On 09/07/2016 05:00 AM, r-devel-requ...@r-project.org wrote:

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).


Have patience Martin.  I read the news in digest form once a day and just saw the 
announcement and this follow-up a few minutes ago.  I haven't had cause to download a new 
copy of R-devel in the last month so the new Sept 5 version hasn't impacted me.


The survival package had one line of code that will need modification, which isn't so bad. 
 It involves the scaled Shoenfeld residuals, for which the formula is r V + 1 beta'; r= 
matrix of residuals with nvar columns and #deaths rows, V=vcov(fit) = variance matrix, and 
then add beta[j] to each column j.  When the number of covariates is 1 the first term of 
this collapsed to a vector *  1x1 matrix, mostly because of how the code was written, 
which was itself the result of evolution over time.   Bottom line is that I don't find 
either the prior behavior or the new one problematic.


Terry T.

__
R-devel@r-project.org mailing list
https://stat.ethz.ch/mailman/listinfo/r-devel

Re: [Rd] R (development) changes in arith, logic, relop with (0-extent) arrays

[Martin Maechler]

> Martin Maechler 
> 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) 
> 2) <1-extent array>  (arith)  

> 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