nlsam.angular_tools
¶
Module Contents¶
Functions¶

Returns the indices of the n closest neighbors (excluding the vector itself) 

Inner function that finds the angle between all vectors of the input. 

Returns a list of subsets that spans the input sets with a greedy algorithm 

Process each shell separately for finding the valid angular neighbors. 
 nlsam.angular_tools.angular_neighbors(vec, n)¶
Returns the indices of the n closest neighbors (excluding the vector itself) given an array of m points with x, y and z coordinates.
Input : A m x 3 array, with m being the number of points, one per line. Each column has x, y and z coordinates for each vector.
Output : A m x n array. Each line has the n indices of the closest n neighbors amongst the m input vectors.
Note : Symmetries are not considered here so a vector and its opposite sign counterpart will be considered far apart, even though in dMRI we consider (x, y, z) and (x, y, z) to be practically identical.
 nlsam.angular_tools._angle(vec)¶
Inner function that finds the angle between all vectors of the input. The diagonal is the angle between each vector and itself, thus 0 everytime. It should not be called as is, since it serves mainly as a shortcut for other functions.
arccos(0) = pi/2, so b0s are always far from everyone in this formulation.
 nlsam.angular_tools.greedy_set_finder(sets)¶
Returns a list of subsets that spans the input sets with a greedy algorithm http://en.wikipedia.org/wiki/Set_cover_problem#Greedy_algorithm
 nlsam.angular_tools.split_shell(bvals, bvecs, block_size, dwis, is_symmetric=False, bval_threshold=25)¶
Process each shell separately for finding the valid angular neighbors. Returns a list of indexes for each shell separately