Find the closest match of a list in a list containing lists

Question

I have a list with two elements like this:

list_a = [27.666521, 85.437447]

and another list like this:

big_list = [[27.666519,          


        

Answer 1

Assumptions:

• You intend to make this type query more than once on the same list of lists
• Both the query list and the lists in your list of lists represent points in a n-dimensional euclidean space (here: a 2-dimensional space, unlike GPS positions that come from a spherical space).

This reads like a nearest neighbor search. Probably you should take into consideration a library dedicated for this, like scikits.ann.

Example:

import scikits.ann as ann
import numpy as np
k = ann.kdtree(np.array(big_list))
indices, distances = k.knn(list_a, 1)

This uses euclidean distance internally. You should make sure, that the distance measure you apply complies your idea of proximity.

You might also want to have a look on Quadtree, which is another data structure that you could apply to avoid the brute force minimum search through your entire list of lists.