Terrence:
Bill's right. It's not clear what output you desire. That's why his result is:
> (i. 2 3) i."1[4
> 3 1
But Devon's is:
> (i. 2 3) ixmd 4
> 1 1
Both are correct, but they're answering different questions. Here's another
possible answer:
4 = i. 2 3
0 0 0
0 1 0
Which leads directly to other formulations of Devon's ixmd :
idx0 =. $ #: I.@:,
idx1 =. 4 $. $.
imx0 =: idx0@:=
imx1 =: idx1@:=
4 imx0 i. 2 3
1 1
4 imx1 i. 2 3
1 1
Which can be extended to seeking any rectangle (cuboid) x in array y :
ptrn =. E.&>/@:((>. - ,)&:(#@:$) ,:@:]^:[&.> ,&:<)
4 idx0@:ptrn i. 2 3
1 1
-Dan
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