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bundles / scipy 1.18.0 / scipy / spatial / _kdtree / KDTree / query_pairs

function

scipy.spatial._kdtree:KDTree.query_pairs

source: /scipy/spatial/_kdtree.py:690

Signature

def query_pairs(self, r, p = 2.0, eps = 0.0, output_type = set)

Summary

Find all pairs of points in self whose distance is at most r.

Parameters

r : positive float

The maximum distance.

p : float, optional

Which Minkowski norm to use. p has to meet the condition 1 <= p <= infinity.

eps : float, optional

Approximate search. Branches of the tree are not explored if their nearest points are further than r/(1+eps), and branches are added in bulk if their furthest points are nearer than r * (1+eps). eps has to be non-negative.

output_type : str, optional

Choose the output container, 'set' or 'ndarray'. Default: 'set'

Returns

results : set or ndarray

Set of pairs (i,j), with i < j, for which the corresponding positions are close. If output_type is 'ndarray', an ndarray is returned instead of a set.

Examples

You can search all pairs of points in a kd-tree within a distance: 
import matplotlib.pyplot as plt
import numpy as np
from scipy.spatial import KDTree
rng = np.random.default_rng()
points = rng.random((20, 2))
✓
plt.figure(figsize=(6, 6))
plt.plot(points[:, 0], points[:, 1], "xk", markersize=14)
✗
[<matplotlib.lines.Line2D object at 0x7fa8e47292b0>]

kd_tree = KDTree(points)
pairs = kd_tree.query_pairs(r=0.2)
✓
for (i, j) in pairs:
    plt.plot([points[i, 0], points[j, 0]],
            [points[i, 1], points[j, 1]], "-r")
✗
[<matplotlib.lines.Line2D object at 0x7fa8e472a270>]
[<matplotlib.lines.Line2D object at 0x7fa8e4728590>]
[<matplotlib.lines.Line2D object at 0x7fa8e4729e80>]
[<matplotlib.lines.Line2D object at 0x7fa8e47286e0>]
[<matplotlib.lines.Line2D object at 0x7fa8e4729550>]
[<matplotlib.lines.Line2D object at 0x7fa8e472b230>]
[<matplotlib.lines.Line2D object at 0x7fa8e472bb60>]
[<matplotlib.lines.Line2D object at 0x7fa8e47282f0>]
[<matplotlib.lines.Line2D object at 0x7fa8e472a660>]
[<matplotlib.lines.Line2D object at 0x7fa8e472ba10>]
[<matplotlib.lines.Line2D object at 0x7fa8e472aba0>]
[<matplotlib.lines.Line2D object at 0x7fa8e472b620>]
[<matplotlib.lines.Line2D object at 0x7fa8e4729a90>]
[<matplotlib.lines.Line2D object at 0x7fa8e472a7b0>]
[<matplotlib.lines.Line2D object at 0x7fa8e472a3c0>]
[<matplotlib.lines.Line2D object at 0x7fa8e472b8c0>]
[<matplotlib.lines.Line2D object at 0x7fa8e472b4d0>]
[<matplotlib.lines.Line2D object at 0x7fa8e4728ad0>]
[<matplotlib.lines.Line2D object at 0x7fa8e472a120>]
[<matplotlib.lines.Line2D object at 0x7fa8e4728980>]
[<matplotlib.lines.Line2D object at 0x7fa8e4728d70>]
[<matplotlib.lines.Line2D object at 0x7fa8e4729010>]

plt.show()
✓
fig-621a6e995aa313b4.png

Aliases

  • scipy.spatial.KDTree.query_pairs