As I said, y is a boxed list the first item of which
contains some vector V which needs permutation.
All the other items contain a list of two values,
that’s why I said they represent transpositions.
I could as well have built their product and
then applied that permutation to the vector.
I only mentioned it as an example of /’s usage.
There are some other places where I use it with
a single transposition.
@raul: yes, they’re the same length but they
have been built iteratively (^:)
it was easiest just ;~ing them to the
partial result
and boxing the first was necessary since
the very first item (not a permutation,
it had a different meaning) V would be
computed from has a different shape
@both: as you asked for an example, in one case
V (aka 'buildVfrom > {. y') had shape 50
and the start of > }. y looked like
0 0
1 2
2 12
3 12
4 49
5 5
6 26
7 12
8 37
9 37
10 18
11 49
so there are even identity “transpositions”
that have to be dealt with (no-ops)
Am 30.05.20 um 15:39 schrieb Brian Schott:
Could you please give a sample of your use of your swap.
I can't understand your description or the input(s).
Thanks,
On Sat, May 30, 2020 at 3:27 AM Hauke Rehr <[email protected]> wrote:
[snip]
My last use case was a boxed list consisting of
a 1-d array and a set of transpositions I produced.
I wrote (I bet there are better ways to do it)
swap =: ] {~ ~.@[ C.@; <:@#@]
and applied it on that boxed list.
That actually looked something like 'swap&.>/@:|.' .
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