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5d5638e674
* stat/*: Update functions to take empty matrices Change TorgersonScaling to require an empty matrix. Users who want to reuse data can call Reset now that it is exposed. This function is different than others because the return size is unknown. Forcing the input matrix to be empty makes it clear that the dst matrix will be dynamically resized Fixes #1081.
63 lines
1.4 KiB
Go
63 lines
1.4 KiB
Go
// Copyright ©2016 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 stat_test
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import (
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"fmt"
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"gonum.org/v1/gonum/mat"
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"gonum.org/v1/gonum/stat"
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)
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func ExamplePC() {
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// iris is a truncated sample of the Fisher's Iris dataset.
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n := 10
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d := 4
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iris := mat.NewDense(n, d, []float64{
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5.1, 3.5, 1.4, 0.2,
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4.9, 3.0, 1.4, 0.2,
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4.7, 3.2, 1.3, 0.2,
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4.6, 3.1, 1.5, 0.2,
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5.0, 3.6, 1.4, 0.2,
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5.4, 3.9, 1.7, 0.4,
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4.6, 3.4, 1.4, 0.3,
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5.0, 3.4, 1.5, 0.2,
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4.4, 2.9, 1.4, 0.2,
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4.9, 3.1, 1.5, 0.1,
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})
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// Calculate the principal component direction vectors
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// and variances.
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var pc stat.PC
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ok := pc.PrincipalComponents(iris, nil)
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if !ok {
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return
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}
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fmt.Printf("variances = %.4f\n\n", pc.VarsTo(nil))
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// Project the data onto the first 2 principal components.
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k := 2
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var proj mat.Dense
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var vec mat.Dense
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pc.VectorsTo(&vec)
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proj.Mul(iris, vec.Slice(0, d, 0, k))
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fmt.Printf("proj = %.4f", mat.Formatted(&proj, mat.Prefix(" ")))
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// Output:
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// variances = [0.1666 0.0207 0.0079 0.0019]
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//
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// proj = ⎡-6.1686 1.4659⎤
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// ⎢-5.6767 1.6459⎥
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// ⎢-5.6699 1.3642⎥
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// ⎢-5.5643 1.3816⎥
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// ⎢-6.1734 1.3309⎥
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// ⎢-6.7278 1.4021⎥
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// ⎢-5.7743 1.1498⎥
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// ⎢-6.0466 1.4714⎥
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// ⎢-5.2709 1.3570⎥
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// ⎣-5.7533 1.6207⎦
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}
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