11:16 a.m.
Hi,
is this failure expected or/and a bug?:
<hansl>
matrix m = I(2)
strings ms = defarray("a", "b")
colnames(m, ms) # works
print m
colnames(m, defarray("a", "b")) # fails
print m
</hansl>
Last month's snapshot -- should I update?
thanks,
sven
1:56 p.m.
On Tue, 14 Mar 2017, Sven Schreiber wrote:
Hi,
is this failure expected or/and a bug?:
<hansl>
matrix m = I(2)
strings ms = defarray("a", "b")
colnames(m, ms) # works
print m
colnames(m, defarray("a", "b")) # fails
print m
</hansl>
I wouldn't really say it's a bug. As things stand defarray() needs a
type specification, so we know what sort of array the user wants and
can check the putative elements for type-correctness.
In principle, I suppose that if we didn't get a type specification in
advance we could evaluate all the putative members and if they're all
of the same (acceptable) type, set the array type afterwards.
Allin
2:55 p.m.
On Tue, 14 Mar 2017, Allin Cottrell wrote:
On Tue, 14 Mar 2017, Sven Schreiber wrote:
> Hi,
> is this failure expected or/and a bug?:
>
> <hansl>
> matrix m = I(2)
>
> strings ms = defarray("a", "b")
> colnames(m, ms) # works
> print m
>
> colnames(m, defarray("a", "b")) # fails
> print m
> </hansl>
I wouldn't really say it's a bug. As things stand defarray() needs a type
specification, so we know what sort of array the user wants and can check the
putative elements for type-correctness.
In principle, I suppose that if we didn't get a type specification in advance
we could evaluate all the putative members and if they're all of the same
(acceptable) type, set the array type afterwards.
Well, it turned out that was quite straightforward to implement, so
it's now in git. Anonymous usage of defarray() was not a use-case that
had occurred to me, but no real reason why it shouldn't work.
This also means that, e.g.,
M = defarray(I(2), {1,2,3})
will now work to give you an array of matrices without having to
specify the "matrices" type. However, the array() constructor still
requires a type specifier. You can't create an array of unspecified
type: the specification must either come up front or be implicit in
the set of arguments (defarray only).
Allin
3:01 p.m.
Am 14.03.2017 um 15:55 schrieb Allin Cottrell:
M = defarray(I(2), {1,2,3})
will now work to give you an array of matrices without having to specify
the "matrices" type.
Will this work?:
matrix a = {1; 2}
m = defarray(a'a)
I'm asking because sometimes gretl converts a 1x1 matrix to a scalar,
and an array of scalars isn't possible (because it's already covered by
a matrix type, of course).
thanks,
sven
3:18 p.m.
On Tue, 14 Mar 2017, Sven Schreiber wrote:
Am 14.03.2017 um 15:55 schrieb Allin Cottrell:
> M = defarray(I(2), {1,2,3})
>
> will now work to give you an array of matrices without having to specify
> the "matrices" type.
Will this work?:
matrix a = {1; 2}
m = defarray(a'a)
I'm asking because sometimes gretl converts a 1x1 matrix to a scalar, and an
array of scalars isn't possible (because it's already covered by a matrix
type, of course).
Good question, but Yes, it works. An on-the-fly result of matrix
multiplication, such as a'a, remains of matrix type internally. It's
only on assignment that -- if it's 1 x 1 and no type has been
specified for the LHS -- we "cast" it to a scalar.
Allin
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