>>>>> "LP" == Luke Palmer <[EMAIL PROTECTED]> writes:
LP> On 5/18/05, Anthony Heading <[EMAIL PROTECTED]> wrote:
>> Is there a way to target hyperoperators at different axes of a
>> multi-dimensional array? This is an attractive feature of
>> various APL-like languages, viz. e.g. in J:
>>
>> a =. 2 5 $ i. 7 - a simple 2-by-5 array
>> a
>> 0 1 2 3 4 - like this
>> 5 6 0 1 2
>>
>>
>> +/"1 a - sum reduce over axis 1
>> 10 14
LP> [+]<< @a
>> +/"2 a - sum reduce over axis 2
>> 5 7 2 4 6
LP> Can't think of any for this one. Or maybe it's this one that I can
LP> think of it for, and the other one which I can't.
i can't spit out the syntax but here is the conceptual way i would do
it. we do have multidimensional slices so we could grab each slice
(maybe with zip?) and pass that to [+] and then grab the list of results
back into a array/matrix with one less dimension than the original.
so it would be something like this: (very wacko pseudo code):
@in[ * ; 2 ; * ] ==>
map [+] ==>
@out
that was an (bad) attempt to slice the third entry in the second
dimension to be summed.
LP> I think we're beginning to re-invent PDL. Poorly.
but is there a p6 pdl yet? they may not need much with multi-dim ops,
slices, hyper and reduce all built in! also with type int (patform
ints), they can get the dense storage needed (but losing any dimensional
flexibility).
uri
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Uri Guttman ------ [EMAIL PROTECTED] -------- http://www.stemsystems.com
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