Hi:I would like to write an algorithm that operates on a multi-array and am having trouble figuring out how to work with arbitrary numbers of dimensions. A simplified version of my problem that captures all of the types of access I need is:
1) You have a multi-array of (statically defined at compilation) dimensionality N.
2) This data is filled in, but the number of elements in each dimension will frequently be different.
3) Write a function that takes a reference to this multiarray and assigns it the value which is the sum of all of the actual indices(this is contrived, but if I can solve this, I can solve my problem... The key is I need an iterator moving through all dimensions, and I need the index numbers for my calculations).
Here is some pseudocode that gives the kind of iterator I would love to have:
template<int N>
void test_setting(multi_array<double, N>& arr)
{
//HERE IS PSEUDOCODE: LETS SAY THERE WAS A WAY TO GET AN INDEX THAT YIELDED THE ACTUAL INDEX NUMBERS BUT STILL ACTED AS A POINTER.
for(FANCYINDEX = arr.begin(); FANCYINDEX != arr.end(); ++FANCYINDEX)
{
boost::array<int, N> indicies = FANCYINDEX.get_indices()
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; //SAY IT RETURNED THE ACTUAL NUMBERS
*FANCYINDEX = sum(indicies);
//Alternatively, could we go: arr(indicies) = sum(indices); if there is no way for it to be a proper pointer.
}
}
//TO CALL:
const int NUMDIMS = 3; //Static at compile time.
int n1 = 3; //These might be dynamic.
int n2 = 4;
int n3 = 5;
boost::multi_array<double, NUMDIMS> A(boost::extents[n1][n2][n3]);
test_setting(A);
Any ideas on how this could be implemented without too much code?
Thanks,
Jesse