Hi Brian,
I ran and tested your first two solutions
trim1 =: >@(tess &(cp;._3))@:(<"1)
trim1 i. 7 10 3
33 34 35
42 43 44
51 52 53
123 124 125
132 133 134
141 142 143
100000 timespacex 'trim1 i. 7 10 3'
6.47903e_6 21632
trim2 =: ,"_2@(tess &(cp;._3))@:(]"1)
(trim1 -: trim2) i. 7 10 3
1
100000 timespacex 'trim2 i. 7 10 3'
7.05994e_6 20096
To clean up the dangling (<"1) I made a monadic fork with the same performance:
trima=:>@(tess cp;._3 <"1) NB. Monadic fork
(trim1 -: trima) i. 7 10 3
1
100000 timespacex 'trima i. 7 10 3'
6.32724e_6 21376
...then did a dyadic version which could be useful if you wanted to use
different values for tess. Same speed but a little less space used.
trimb=:>@([&cp;._3 <"1) NB. Dyadic
tess (trim1@:] -: trimb) i. 7 10 3 NB. Dyadic trimb compared to trim1
1
100000 timespacex 'tess trimb i. 7 10 3'
6.23274e_6 17920
...then went with shorter code with a dyadic hook but more space than trimb.
trimc=:>@(cp;._3 <"1) NB. Dyadic hook
tess (trim1@:] -: trimc) i. 7 10 3
1
100000 timespacex 'tess trimc i. 7 10 3'
6.36805e_6 21504
...and finally this dyadic version based on the (]"1) dangler
trimd=: ,"_2@(cp;._3)
tess (trim1@:] -: trimd) i. 7 10 3
1
100000 timespacex 'tess trimd i. 7 10 3'
7.16478e_6 20224
Not any significant differences in speed but trimb uses the least space.
Hope this helps.
Cheers, bob
> On Jun 1, 2017, at 5:32 AM, Brian Schott <[email protected]> wrote:
>
> cp =: (<1 1)&{ NB. center pixel of 3x3
> tess =: 2 2$3 NB. tesselate
> trim =: >@(tess &(cp;._3))@:(<"1)
> trim =: ,"_2@(tess &(cp;._3))@:(]"1)
>
> I have found the trim's above both accomplish the desired result. My
> question especially is, how can the rank "1 in the latter trim be
> incorporated without the trailing @(). Any other suggestions to achieve
> speed improvements would be appreciated, too.
>
> I am experimenting with the following phrase, for example, and when
> applying rank directly, without the @:() I get length error.
>
> trim i. 7 10 3 NB. a fake rgb image argument
>
> Thank you,
>
> --
> (B=)
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