C++ sorting and keeping track of indexes -
using c++, , standard library, want sort sequence of samples in ascending order, want remember original indexes of newly samples. for example, have set, or vector, or matrix of samples a : [5, 2, 1, 4, 3] . want sort these b : [1,2,3,4,5] , want remember original indexes of values, can set be: c : [2, 1, 4, 3, 0 ] - corresponds index of each element in 'b', in original 'a'. for example, in matlab can do: [a,b]=sort([5, 8, 7]) = 5 7 8 b = 1 3 2 can see way this? using c++11 lambdas template <typename t> vector<size_t> sort_indexes(const vector<t> &v) { // initialize original index locations vector<size_t> idx(v.size()); iota(idx.begin(), idx.end(), 0); // sort indexes based on comparing values in v sort(idx.begin(), idx.end(), [&v](size_t i1, size_t i2) {return v[i1] < v[i2];}); return idx; } now can use returned index vector in iterations such as for (auto i: sort_indexes(v)) { c
