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POHow Does One Sum Dimensions of an Array Specified at Run-Time?
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copied!<p>I am working on a function to establish the entropy of a distribution. It uses a copula, if any are familiar with that. I need to sum up the values in the array based on which dimensions are "cared about."</p> <p>Example: Consider the following example... </p> <pre> Dimension 0 (across) _ _ _ _ _ _ _ _ _ _ _ _ _ |_ 0 _|_ 0 _|_ 0 _|_ 2 _| Dimension 1 |_ 1 _|_ 0 _|_ 2 _|_ 0 _| (down) |_ 0 _|_ 3 _|_ 0 _|_ 6 _| |_ 0 _|_ 0 _|_ 0 _|_ 0 _| I "care about" dimension 0 only, and "don't care" about the rest (dim 1). Summing this array with the above specifications will "collapse" the "stacks" of dimension 1 down to a single 4 x 1 array: _ _ _ _ _ _ _ _ _ _ _ _ _ |_ 1 _|_ 3 _|_ 2 _|_ 8 _| This can then be summed, or have any operation performed. </pre> <p>I need to do this with an array of 'n' dimensions, which could feasibly be 20. Also, I need to be able to do this, caring about certain dimensions, and collapsing the rest. I am having an especially hard time with this because I cant visualize 20 dimensions :p . If anyone could help me set up some c/c++ code to collapse/sum, I would be very very grateful. </p> <h3>Update:</h3> <p>Just got home. Here is some info to answer your questions:</p> <ol> <li>Sorry for rolling back the edits, I was hoping when I clicked roll-back it would show me the changes so I could see what I messed up, a bit like wikipedia. This wasn't the case, as I found out.</li> <li>@jeff - What doesnt make sense? I am using this great service for (what I think is) a legit reason. I want to get better at my hobby, which is all it is, as I am in high school. Many of my posts regard implementing a genetic algorithm (This post, sparsearray, rank an array, pointer manipulation).</li> <li>I am using a sparse array representation, as it is possible to exceed the number of molecules in the universe using a traditional (dense) array. For now, the implementation of the sparsearray itself doesnt matter a whole lot, as I am working to make it work with a standard array before going to a sparse representation. For those who havent seen my previous questions, I am using a binary search tree as the structure to contain the sparse array points, and a "driver" function to traverse the tree as necessary, returning whatever the function is designed to do. This is flexible, so I can accomodate a lot of different methods of accessing the array. </li> <li>The structure is a hypercube, and the number of dimensions is specified at run time, as well as the length of each dimension (which are all the same, as it is a hypercube).</li> </ol> <p>Thanks everyone for your imput.</p>

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