On 12/03/2018 2:43 PM, Bert Gunter wrote:
Please stop this line of queries/"suggestions/speculations and read the
relevant docs **carefully**.
For example, from ?"=="
"Note
Do not use == and != for tests, such as in if expressions, where you must
get a single TRUE or FALSE. Unless you are absolutely sure that nothing
unusual can happen, you should use the identical
<http://127.0.0.1:22171/help/library/base/help/identical> function instead.
"
But stopifnot(expr) is not a test where you must get a single TRUE or
FALSE. See the Details section on its help page, or read its
Description carefully (where "all" is used in the technical sense of the
all() function), ignoring the final few words which seem to suggest that
c(TRUE, TRUE) is not okay.
Duncan Murdoch
So you have already violated that specific warning, which led to the
confusion you evidence. Specifically:
Matrix(1)== Matrix(1)
1 x 1 Matrix of class "lsyMatrix"
[,1]
[1,] TRUE
That is, the result is not a logical but a (S4) object of class "lsyMatrix"
that contains a logical. Whence your (expected) error message.
Cheers,
Bert
Bert Gunter
"The trouble with having an open mind is that people keep coming along and
sticking things into it."
-- Opus (aka Berkeley Breathed in his "Bloom County" comic strip )
On Mon, Mar 12, 2018 at 10:53 AM, Stepan Kasal <ka...@ucw.cz> wrote:
Hello,
On Mon, Mar 12, 2018 at 09:30:59AM -0700, William Dunlap wrote:
Why don't you use
stopifnot( all(m1 == m2) )
?
good question. Even though I use
aseert np.all(m1 == m2)
when working with NumPy, I got accustomed to the "handy shortcut"
that I can omit all() with R vectors and matrices.
Then I got trapped with the thing I reported.
On a second thought, omitting all() might have been bad idea from
the beginning; I should rather write all() routinely.
(It also reminds me that all.equal() is the right one in most cases.)
Is it true that using stopifnot() with non-scalar is considerd bad style?
If yes, could be perhaps stopifnot() enhanced to issue a warning to
teach new users of R, at least when they start using library(Matrix)?
If not, then enhancing stopifnot() to handle the case may be a good idea.
I also noticed the following:
a <- Matrix(1)
stopifnot(a == a)
Error: a == a is not TRUE
if(a==a)print(1)
Error in if (a == a) print(1) : argument is not interpretable as logical
Neither does work, but the first error message is much more confusing.
When thinking about it, stopifnot() should really issue a better error
message in this case. Patch attached. But I should perhaps send
it also to R-devel.
Stepan Kasal
On Mon, Mar 12, 2018 at 8:15 AM, Stepan Kasal <ka...@ucw.cz> wrote:
Hello,
I stumbled over a problem:
stopifnot(m1 == m2)
It works with vector or matrix, but does not work for classes from
Matrix
package.
In the source of stopifnot(), there is all(m1 == m2) that would just
work,
but there is also is.logical(m1 == m2) that id FALSE.
Would it be possible if Matrix package redefined stopifnot() ?
(If there is a bug tracking database for package Matrix, I would be
happy
to insert this report there.)
Thank you very much for the package,
Stepan Kasal
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