On 06/13/11 15:06, kelvSYC wrote:

On Jun 13, 2011, at 8:19 AM, Larry Evans wrote:

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On 06/13/11 06:37, kelvSYC wrote:

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So that the wheel doesn't have to be reinvented if it's already out there, is there something in boost that will take a bunch of sequences (lists, say) and return a sequence containing the cartesian product all of them, either as a tuple or after applying a function to them?

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For example, is there something in boost that will, given a bunch of lists of integers, return a list of integers formed by multiplying together one member from each list?

To be more concrete, say you have:

std::vector<int> x({1,2,3}); std::vector<int> y({4,5});

and what you want is something like:

std::vector z ( { { 4, 5} , { 8, 10} , { 12, 15} } };

Is that about right?

No, just a straight up cartesian product.

The example I provided was meant to be an example of, as you say, "applying a function to them". In my example, that would be the std::multiply<int>() functor. The "straight up cartesian product" would be produced by using std::make_pair as the function.

So I'd want z to be equal to

std::vector({{1,4}, {1,5}, {2,4}, {2,5}, {3,4}, {3,5}});

Is there something in boost that will give me this sequence (or at least iterators therein?)

I pretty sure there is none since the thread I mentioned previously did not mention one and people replying to that thread indicated it would be desirable. -regards, Larry

On 06/13/11 17:54, Larry Evans wrote:

On 06/13/11 15:25, Larry Evans wrote:

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On 06/13/11 15:06, kelvSYC wrote:

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On Jun 13, 2011, at 8:19 AM, Larry Evans wrote:

[snip]

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So I'd want z to be equal to

std::vector({{1,4}, {1,5}, {2,4}, {2,5}, {3,4}, {3,5}});

Is there something in boost that will give me this sequence (or at least iterators therein?)

I pretty sure there is none since the thread I mentioned previously did not mention one and people replying to that thread indicated it would be desirable.

The attached code, using boost multi_array, produces output shown in 2nd attachment. [snip] The attached code produces same output but is clearer and probably faster because, instead of using div, it just uses ++, although it does have 2 loops instead of just one.