github.com/gopherd/gonum@v0.0.4/spatial/kdtree/kdtree_simple_example_test.go (about)

     1  // Copyright ©2019 The Gonum Authors. All rights reserved.
     2  // Use of this source code is governed by a BSD-style
     3  // license that can be found in the LICENSE file.
     4  
     5  package kdtree_test
     6  
     7  import (
     8  	"fmt"
     9  	"math"
    10  
    11  	"github.com/gopherd/gonum/spatial/kdtree"
    12  )
    13  
    14  func ExampleTree() {
    15  	// Example data from https://en.wikipedia.org/wiki/K-d_tree
    16  	points := kdtree.Points{{2, 3}, {5, 4}, {9, 6}, {4, 7}, {8, 1}, {7, 2}}
    17  
    18  	t := kdtree.New(points, false)
    19  	q := kdtree.Point{8, 7}
    20  	p, d := t.Nearest(q)
    21  	fmt.Printf("%v is closest point to %v, d=%f\n", p, q, math.Sqrt(d))
    22  	// Output:
    23  	// [9 6] is closest point to [8 7], d=1.414214
    24  }
    25  
    26  func ExampleTree_bounds() {
    27  	// Example data from https://en.wikipedia.org/wiki/K-d_tree
    28  	points := kdtree.Points{{2, 3}, {5, 4}, {9, 6}, {4, 7}, {8, 1}, {7, 2}}
    29  
    30  	t := kdtree.New(points, true)
    31  	fmt.Printf("Bounding box of points is %+v\n", t.Root.Bounding)
    32  	// Output:
    33  	// Bounding box of points is &{Min:[2 1] Max:[9 7]}
    34  }
    35  
    36  func ExampleTree_Do() {
    37  	// Example data from https://en.wikipedia.org/wiki/K-d_tree
    38  	points := kdtree.Points{{2, 3}, {5, 4}, {9, 6}, {4, 7}, {8, 1}, {7, 2}}
    39  
    40  	// Print all points in the data set within 3 of (3, 5).
    41  	t := kdtree.New(points, false)
    42  	q := kdtree.Point{3, 5}
    43  	t.Do(func(c kdtree.Comparable, _ *kdtree.Bounding, _ int) (done bool) {
    44  		// Compare each distance and output points
    45  		// with a Euclidean distance less than 3.
    46  		// Distance returns the square of the
    47  		// Euclidean distance between points.
    48  		if q.Distance(c) <= 3*3 {
    49  			fmt.Println(c)
    50  		}
    51  		return
    52  	})
    53  	// Unordered output:
    54  	// [2 3]
    55  	// [4 7]
    56  	// [5 4]
    57  }
    58  
    59  func ExampleTree_DoBounded() {
    60  	// Example data from https://en.wikipedia.org/wiki/K-d_tree
    61  	points := kdtree.Points{{2, 3}, {5, 4}, {9, 6}, {4, 7}, {8, 1}, {7, 2}}
    62  
    63  	// Find all points within the bounding box ((3, 3), (6, 8))
    64  	// and print them with their bounding boxes and tree depth.
    65  	t := kdtree.New(points, true) // Construct tree with bounding boxes.
    66  	b := &kdtree.Bounding{
    67  		Min: kdtree.Point{3, 3},
    68  		Max: kdtree.Point{6, 8},
    69  	}
    70  	t.DoBounded(b, func(c kdtree.Comparable, bound *kdtree.Bounding, depth int) (done bool) {
    71  		fmt.Printf("p=%v bound=%+v depth=%d\n", c, bound, depth)
    72  		return
    73  	})
    74  	// Output:
    75  	// p=[5 4] bound=&{Min:[2 3] Max:[5 7]} depth=1
    76  	// p=[4 7] bound=&{Min:[4 7] Max:[4 7]} depth=2
    77  }