count_neighbors(other, r, p=2.0)¶
Count how many nearby pairs can be formed.
Count the number of pairs (x1,x2) can be formed, with x1 drawn from self and x2 drawn from other, and where
distance(x1, x2, p) <= r. This is the “two-point correlation” described in Gray and Moore 2000, “N-body problems in statistical learning”, and the code here is based on their algorithm.
other : KDTree instance
The other tree to draw points from.
r : float or one-dimensional array of floats
The radius to produce a count for. Multiple radii are searched with a single tree traversal.
p : float, 1<=p<=infinity, optional
Which Minkowski p-norm to use
result : int or 1-D array of ints
The number of pairs. Note that this is internally stored in a numpy int, and so may overflow if very large (2e9).