On 03/12/08 06:10, Larry Evans wrote:
On 03/11/08 22:42, Max Motovilov wrote: [snip]
I apologize in advance if something along these lines is already available; however current public documentation doesn't mention such a facility and a brief glance into SVN did not reveal one either...
product_view
Description: provides a view of a Cartesian product of multiple sequences. Modeled after zip_view in that it expects a sequence [of length n] of sequences S1...Sn as its argument and lazily generates a sequence [of length Prod{1...n}( size< Si > )] of sequences S1[1]...Sn[1] through S1[n]...Sn[n]. Whew... I know I can write better documentation than that if I put my mind to it :(
From Prod[1..n}(size<Si>} it appears this just flattens a list 1 level. IOW: from: list < list< A0_0, A0_1> , list< A1_0, A1_1> ... , list< An_0, An_1. > it produces: list < A0_0, A0_1 , A1_0, A1_1 ... , An_0, An_1 >
Is that right?
OOPS, that would be Sum{1..n}(size<Si>} so I guess this would be more like an outer-product where for: Input: list < list<A0_0, A0_1> //S1 , list<A1_0, A1_1> //S2
Output: list < list<A0_0, A1_0> //s1[1]...S1[2]? Nope, this is S1[1]...S2[1] , list<A0_0, A2_0> , list<A0_1, A1_0> , list<A0_1, A1_1>
Here, since sizes of inputs are 2 and 2, size of output is 2*2=4. But that's inconsistent with: sequences S1[1]...Sn[1] through S1[n]...Sn[n] Could you please clarify? I'm lost ;(