Mikael Jagan
2023-Nov-08 16:13 UTC
[Rd] c(NA, 0+1i) not the same as c(as.complex(NA), 0+1i)?
So, to summarize, the open questions are:
(1) Should as.complex(NA_character_) give complex(r=NA_real_, i=0)
instead of NA_complex_?
(2) Should the first argument in c(NA, x) and c(NA_integer_, x),
where typeof(x) == "complex", be promoted to
complex(r=NA_real_, i=0)
instead of NA_complex_?
My opinions:
(1) No. The imaginary part of the result of parsing the strings
"<b>i",
"<a>+<b>i", and "<a>-<b>i"
can be nonzero.
Consider, e.g., Im(eval(str2lang("0+1i"))) and
Im(as.complex("0+1i")).
If NA_character_ means "a string with unknown content", then
we should
not assume that the string is parsed as a real number.
(2) Yes. I'd very much like to preserve the identity of c(Im(NA),
Im(x))
and Im(c(NA, x)) for atomic (excluding raw, character) vectors
'x'.
And while typing this response I noticed the following in current R-devel and
current R-patched:
> 0+1i
[1] 0+1i
> 1i
[1] 0+1i
> as.complex("0+1i")
[1] 0+1i
> as.complex("1i")
[1] NA
Warning message:
NAs introduced by coercion
That warning seems wrong to me ...
Mikael
On 2023-11-07 6:00 am, r-devel-request at r-project.org
wrote:>>>>>> Michael Chirico
>>>>>> on Mon, 6 Nov 2023 23:18:40 -0800 writes:
> > Thanks Martin. My hang-up was not on what the outcome of
as.complex(NA)
> > should be, but rather, how I should read code like c(x, y)
generally. Till
> > now, I have thought of it like 'c(x, y)' is c(as(x,
typeof(y)), y)` when
> > "type(y) > type(x)". Basically in my mind,
"coercion" in R <->
> > as.<newtype>(.) (or coerceVector() in C).
>
> > So I tracked down the source (which admittedly has been this way
for much
> > longer than the present discussion) to see what exactly c() is
doing in
> > this case:
>
>
>https://github.com/r-devel/r-svn/blob/71e7480b07767f3b7d5c45a4247959aa4d83d910/src/main/bind.c#L418-L425
>
> > And indeed! It's not "coercion" in the sense I just
described... there's a
> > branch for the 'x == NA_LOGICAL' case to_convert_ to
NA_complex_.
>
> Yes; "of course" ... still, I did not answer your main question,
> as you did ask +/- if c() should not get an adjustment to the
> new as.complex(<numeric-alike>) |--> (Re = NA, Im = 0)
> behavior.
>
> And that is still a valid open question. ... contrary to what I
> wrote yesterday; sorry for that "answering a different
> question".
>
> Martin
>
>
> > On Mon, Nov 6, 2023 at 3:08?AM Martin Maechler<maechler at
stat.math.ethz.ch>
> > wrote:
>
> >> >>>>> Michael Chirico
> >> >>>>> on Sun, 5 Nov 2023 09:41:42 -0800
writes:
> >>
> >> > This is another follow-up to the thread from September
> >> > "Recent changes to as.complex(NA_real_)".
> >>
> >> > A test in data.table was broken by the changes for NA
> >> > coercion to complex; the breakage essentially comes from
> >>
> >> > c(NA, 0+1i)
> >> > # vs
> >> > c(as.complex(NA), 0+1i)
> >>
> >> > The former is the output we tested against; the latter
is
> >> essentially (via
> >> > coerceVector() in C) what's generated by our
data.table::shift()
> >>
> >> > However, these are now (r85472) different:
> >>
> >> > Im(c(NA, 0+1i))
> >> > # [1] NA 1
> >> > Im(c(as.complex(NA), 0+1i))
> >> > # [1] 0 1
> >>
> >>
> >> > The former matches the behavior of directly using
NA_complex_:
> >>
> >> > Im(c(NA_complex_, 0+1i))
> >> > # [1] NA 1
> >>
> >> > On R4.3.2, they both match the NA_complex_ behavior:
> >> > Im(c(NA, 0+1i))
> >> > # [1] NA 1
> >> > Im(c(as.complex(NA), 0+1i))
> >> > # [1] NA 1
> >>
> >> > Is this intended behavior, does something need to be
updated for c()
> >> as
> >> > well?
> >>
> >> > Certainly it's messing with my understanding of how
c() behaves,
> >> e.g. in ?c
> >>
> >> >> All arguments are coerced to a common type which is
the type of the
> >> > returned value
> >>
> >> I think you have confused yourself, and everything behaves as
expected:
> >>
> >> As we now have (in R-devel, since {r85233 | maechler |
2023-09-29 })
> >>
> >> ? ?as.complex(x)? now returns ?complex(real=x, imaginary=0)?
> >> for_all_ numerical and logical ?x?, notably also for ?NA?
> >> or ?NA_integer_?.
> >>
> >> ==> as.complex(NA) is indeed complex(real = NA, imaginary
= 0)
> >>
> >> And now, in your
> >>
> >> c(as.complex(NA), 0+1i)
> >>
> >> you are calling c() on two complex numbers, i.e., there
is*no* coercion
> >> (and c(.) is rather "trivial"), and the same is
true for
> >>
> >> c(NA_complex_, 0+1i)
> >>
> >>
> >> However, in 85233, I had only modified & added examples
to ?as.complex,
> >> and now have added more (corresponding to the above NEWS
entry);
> -> svn rev 85475
> >>
> >> .............
> >>
> >> The underlying "dilemma" that nobody can help us
with is that
> >> "almost infinitely" many different complex numbers
z fulfill
> >> is.na(z) |--> TRUE
> >> and only one of them is NA_complex_ and that may be
unintuitive.
> >>
> >> OTOH, we already have for the doubles that there are at least
two
> >> different x fulfulling is.na(x), namely NaN and NA
> >> and from C's point of view there are even considerably
more
> >> different NaN's .. but now I'm definitely digressing.
> >>
> >> Martin
> >>
Martin Maechler
2023-Nov-09 08:13 UTC
[Rd] c(NA, 0+1i) not the same as c(as.complex(NA), 0+1i)?
>>>>> Mikael Jagan >>>>> on Wed, 8 Nov 2023 11:13:18 -0500 writes:> So, to summarize, the open questions are: > (1) Should as.complex(NA_character_) give complex(r=NA_real_, i=0) > instead of NA_complex_? > (2) Should the first argument in c(NA, x) and c(NA_integer_, x), > where typeof(x) == "complex", be promoted to complex(r=NA_real_, i=0) > instead of NA_complex_? > My opinions: > (1) No. The imaginary part of the result of parsing the strings "<b>i", > "<a>+<b>i", and "<a>-<b>i" can be nonzero. > Consider, e.g., Im(eval(str2lang("0+1i"))) and Im(as.complex("0+1i")). > If NA_character_ means "a string with unknown content", then we should > not assume that the string is parsed as a real number. > (2) Yes. I'd very much like to preserve the identity of c(Im(NA), Im(x)) > and Im(c(NA, x)) for atomic (excluding raw, character) vectors 'x'. > And while typing this response I noticed the following in current R-devel and > current R-patched: >> 0+1i > [1] 0+1i >> 1i > [1] 0+1i >> as.complex("0+1i") > [1] 0+1i >> as.complex("1i") > [1] NA > Warning message: > NAs introduced by coercion > That warning seems wrong to me ... Well, actually, as we now have had the parser accept 1i or 7i, 3.14i etc I think that it's not the *warning* that is wrong, but rather the *result* : Why should as.complex("1i") be different from one of these?> 1i[1] 0+1i> str2lang("1i")[1] 0+1i> scan(textConnection("1i"), complex())Read 1 item [1] 0+1i>> Mikael > On 2023-11-07 6:00 am, r-devel-request at r-project.org wrote: >>>>>>> Michael Chirico >>>>>>> on Mon, 6 Nov 2023 23:18:40 -0800 writes: >> > Thanks Martin. My hang-up was not on what the outcome of as.complex(NA) >> > should be, but rather, how I should read code like c(x, y) generally. Till >> > now, I have thought of it like 'c(x, y)' is c(as(x, typeof(y)), y)` when >> > "type(y) > type(x)". Basically in my mind, "coercion" in R <-> >> > as.<newtype>(.) (or coerceVector() in C). >> >> > So I tracked down the source (which admittedly has been this way for much >> > longer than the present discussion) to see what exactly c() is doing in >> > this case: >> >> >https://github.com/r-devel/r-svn/blob/71e7480b07767f3b7d5c45a4247959aa4d83d910/src/main/bind.c#L418-L425 >> >> > And indeed! It's not "coercion" in the sense I just described... there's a >> > branch for the 'x == NA_LOGICAL' case to_convert_ to NA_complex_. >> >> Yes; "of course" ... still, I did not answer your main question, >> as you did ask +/- if c() should not get an adjustment to the >> new as.complex(<numeric-alike>) |--> (Re = NA, Im = 0) >> behavior. >> >> And that is still a valid open question. ... contrary to what I >> wrote yesterday; sorry for that "answering a different >> question". >> >> Martin >> >> >> > On Mon, Nov 6, 2023 at 3:08?AM Martin Maechler<maechler at stat.math.ethz.ch> >> > wrote: >> >> >> >>>>> Michael Chirico >> >> >>>>> on Sun, 5 Nov 2023 09:41:42 -0800 writes: >> >> >> >> > This is another follow-up to the thread from September >> >> > "Recent changes to as.complex(NA_real_)". >> >> >> >> > A test in data.table was broken by the changes for NA >> >> > coercion to complex; the breakage essentially comes from >> >> >> >> > c(NA, 0+1i) >> >> > # vs >> >> > c(as.complex(NA), 0+1i) >> >> >> >> > The former is the output we tested against; the latter is >> >> essentially (via >> >> > coerceVector() in C) what's generated by our data.table::shift() >> >> >> >> > However, these are now (r85472) different: >> >> >> >> > Im(c(NA, 0+1i)) >> >> > # [1] NA 1 >> >> > Im(c(as.complex(NA), 0+1i)) >> >> > # [1] 0 1 >> >> >> >> >> >> > The former matches the behavior of directly using NA_complex_: >> >> >> >> > Im(c(NA_complex_, 0+1i)) >> >> > # [1] NA 1 >> >> >> >> > On R4.3.2, they both match the NA_complex_ behavior: >> >> > Im(c(NA, 0+1i)) >> >> > # [1] NA 1 >> >> > Im(c(as.complex(NA), 0+1i)) >> >> > # [1] NA 1 >> >> >> >> > Is this intended behavior, does something need to be updated for c() >> >> as >> >> > well? >> >> >> >> > Certainly it's messing with my understanding of how c() behaves, >> >> e.g. in ?c >> >> >> >> >> All arguments are coerced to a common type which is the type of the >> >> > returned value >> >> >> >> I think you have confused yourself, and everything behaves as expected: >> >> >> >> As we now have (in R-devel, since {r85233 | maechler | 2023-09-29 }) >> >> >> >> ? ?as.complex(x)? now returns ?complex(real=x, imaginary=0)? >> >> for_all_ numerical and logical ?x?, notably also for ?NA? >> >> or ?NA_integer_?. >> >> >> >> ==> as.complex(NA) is indeed complex(real = NA, imaginary = 0) >> >> >> >> And now, in your >> >> >> >> c(as.complex(NA), 0+1i) >> >> >> >> you are calling c() on two complex numbers, i.e., there is*no* coercion >> >> (and c(.) is rather "trivial"), and the same is true for >> >> >> >> c(NA_complex_, 0+1i) >> >> >> >> >> >> However, in 85233, I had only modified & added examples to ?as.complex, >> >> and now have added more (corresponding to the above NEWS entry); -> svn rev 85475 >> >> >> >> ............. >> >> >> >> The underlying "dilemma" that nobody can help us with is that >> >> "almost infinitely" many different complex numbers z fulfill >> >> is.na(z) |--> TRUE >> >> and only one of them is NA_complex_ and that may be unintuitive. >> >> >> >> OTOH, we already have for the doubles that there are at least two >> >> different x fulfulling is.na(x), namely NaN and NA >> >> and from C's point of view there are even considerably more >> >> different NaN's .. but now I'm definitely digressing. >> >> >> >> Martin >> >>
Apparently Analagous Threads
- c(NA, 0+1i) not the same as c(as.complex(NA), 0+1i)?
- c(NA, 0+1i) not the same as c(as.complex(NA), 0+1i)?
- c(NA, 0+1i) not the same as c(as.complex(NA), 0+1i)?
- c(NA, 0+1i) not the same as c(as.complex(NA), 0+1i)?
- c(NA, 0+1i) not the same as c(as.complex(NA), 0+1i)?