How to get max/min element from a boost multiarray

Question

I'm wondering a simple way to find the maximum/minimum element of a boost multiarray, an object of 3 indices as the following:

int iDepth=10,iWidth=10,iHeight=10;
boost::multi_array<GLfloat, 3> image(boost::extents[iDepth][iWidth][iHeight]);

`std::min_element` and `std::max_element` should do the trick. — David Brown, Jun 20 '13 at 07:40
Yes, but I don't understand the form of iterators to pass to this STL functions. — linello, Jun 20 '13 at 07:41

score 2 · Answer 1 · answered Jan 22 '14 at 15:29

2

This should work :

std::max_element( image.origin(), image.origin() + image.num_elements());

answered Jan 22 '14 at 15:29

tunc

This is not correct for array that do not start at `[0][0]...`. See my answer. – alfC Dec 22 '21 at 10:20

score 0 · Answer 2 · answered Dec 22 '21 at 10:20

Using member data() is more correct because:

ensures that image is actually a contiguous (compact array).
scans from the beginning of the array, even if the first elements is not [0][0].... (origin() means the address of [0][0]... even if the array "starts" at a different point, e.g. [1][1]....

std::max_element( image.data(), image.data() + image.num_elements());

score -2 · Answer 3 · answered Jun 20 '13 at 07:40

-2

Did you try something like:

std::max_element( image.begin(), image.end());

answered Jun 20 '13 at 07:40

Cătălin Pitiș

What should I expect as return type of this function with such iterators as input? – linello Jun 20 '13 at 07:50
Check the documentation, for example from here: http://www.cplusplus.com/reference/algorithm/max_element/ – Cătălin Pitiș Jun 20 '13 at 11:15
The iterators return a multi_array of the next lower dimension which is clearly not what the OP wants a maximum of. – Nobody moving away from SE Nov 12 '13 at 14:09

3 Answers3