c++ - sort n-dimension point and keep track of original index -

i have set of n- dimension point store in vector< vector<double> >

ex a[0][1].............[n], , a[0][0] = x, a[0][1] = y, a[0][2] = z 

and want sort vector of of dimension

ex sort x, y, z ,.........n in ascending order   ex              a[0] = (1,5,3), a[1] = (3,2,1) a[2] = (2,8,4) after sorting index:            0               1             2                 a[0] = (1,5,3), a[1] = (2,8,4) a[2] = (3,2,1) original index :  0               2             1 

i find sort(vector.begin(), vector.end()) can sort how can record original index additional vector?

is there algorithm or c++ feature can solve it?

thx in advance.

you need somehow keep information index. can see 2 ways of doing :

1-since represent point vector, can had dimension represent orginal index :

//adding index info, inportant index last dimension , otherwise sort incorrect for(auto point = vector.begin(),unsigned int index=0;point != vector.end(); ++point,++index){ point->push_back(index) };

then sort same way doing :

sort(vector.begin(), vector.end())

and access original index a[0][n]

the cool thing allow keep track of index in convenient way, need able modify representation of point.

2- other way have external table of indices , sort using custom comp. operator :

you start creating vector of indices

std::vector indices(vector.size());

for(unsigned int index =0;index != indicies.size(); ++point){ indicies[index] = index ; };

//and sort...

std::sort(indices.begin(),indices.end(),[&](unsigned int i,unsigned int j) { return vector[i] < vector[j]})

now need additional level of indirection go trough points in sorted order : a[indices[0]],a[indices[1]],... original position of a[indices[x]] x

the main remember between 2 ways of doing in first move data around , not in second , depending on doing on points, 1 might better order