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75 lines
2.0 KiB
Go
75 lines
2.0 KiB
Go
// Copyright ©2017 The Gonum Authors. All rights reserved.
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// Use of this source code is governed by a BSD-style
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// license that can be found in the LICENSE file.
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package spatial_test
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import (
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"fmt"
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"math"
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"gonum.org/v1/gonum/floats"
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"gonum.org/v1/gonum/mat"
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"gonum.org/v1/gonum/stat/spatial"
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)
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// Euclid is a mat.Matrix whose elements reflects the Euclidean
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// distance between a series of unit-separated points strided
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// to be arranged in an x by y grid.
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type Euclid struct{ x, y int }
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func (e Euclid) Dims() (r, c int) { return e.x * e.y, e.x * e.y }
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func (e Euclid) At(i, j int) float64 {
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d := e.x * e.y
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if i < 0 || d <= i || j < 0 || d <= j {
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panic("bounds error")
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}
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if i == j {
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return 0
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}
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x := float64(j%e.x - i%e.x)
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y := float64(j/e.x - i/e.x)
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return 1 / math.Hypot(x, y)
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}
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func (e Euclid) T() mat.Matrix { return mat.Transpose{Matrix: e} }
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func ExampleGlobalMoransI_areal() {
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locality := Euclid{10, 10}
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data1 := []float64{
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1, 0, 0, 1, 0, 0, 1, 0, 0, 0,
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0, 1, 1, 0, 0, 1, 0, 0, 0, 0,
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1, 0, 0, 1, 0, 0, 0, 0, 1, 0,
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0, 0, 1, 0, 1, 0, 1, 0, 0, 0,
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1, 0, 0, 0, 0, 0, 0, 1, 0, 0,
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0, 0, 0, 0, 1, 0, 0, 0, 0, 0,
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0, 0, 1, 0, 0, 0, 1, 0, 1, 0,
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1, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 1, 0, 1, 0, 1, 0, 0, 0,
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1, 0, 0, 0, 0, 0, 0, 0, 1, 0,
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}
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i1, _, z1 := spatial.GlobalMoransI(data1, nil, locality)
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data2 := []float64{
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 0, 0, 0, 0, 0, 0, 0,
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0, 0, 0, 1, 1, 0, 0, 0, 0, 0,
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0, 0, 1, 1, 1, 1, 0, 0, 0, 0,
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0, 0, 1, 1, 1, 1, 0, 0, 0, 0,
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0, 0, 0, 1, 1, 1, 0, 0, 0, 0,
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0, 0, 0, 0, 1, 0, 0, 0, 1, 0,
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0, 0, 0, 0, 0, 0, 0, 1, 1, 1,
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0, 0, 0, 0, 0, 0, 0, 1, 1, 1,
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0, 0, 0, 0, 0, 0, 0, 1, 1, 1,
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}
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i2, _, z2 := spatial.GlobalMoransI(data2, nil, locality)
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fmt.Printf("%v scattered points Moran's I=%.4v z-score=%.4v\n", floats.Sum(data1), i1, z1)
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fmt.Printf("%v clustered points Moran's I=%.4v z-score=%.4v\n", floats.Sum(data2), i2, z2)
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// Output:
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//
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// 24 scattered points Moran's I=-0.02999 z-score=-1.913
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// 24 clustered points Moran's I=0.09922 z-score=10.52
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}
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