82 lines
1.7 KiB
Go
82 lines
1.7 KiB
Go
package util
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import "math"
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// SequenceProvider is a provider for values for a sequence.
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type SequenceProvider interface {
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Len() int
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GetValue(int) float64
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}
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// Sequence is a utility wrapper for sequence providers.
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type Sequence struct {
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SequenceProvider
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}
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// Each applies the `mapfn` to all values in the value provider.
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func (s Sequence) Each(mapfn func(int, float64)) {
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for i := 0; i < s.Len(); i++ {
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mapfn(i, s.GetValue(i))
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}
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}
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// Map applies the `mapfn` to all values in the value provider,
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// returning a new sequence.
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func (s Sequence) Map(mapfn func(i int, v float64) float64) Sequence {
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output := make([]float64, s.Len())
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for i := 0; i < s.Len(); i++ {
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mapfn(i, s.GetValue(i))
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}
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return Sequence{Array(output)}
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}
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// Average returns the float average of the values in the buffer.
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func (s Sequence) Average() float64 {
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if s.Len() == 0 {
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return 0
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}
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var accum float64
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for i := 0; i < s.Len(); i++ {
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accum += s.GetValue(i)
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}
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return accum / float64(s.Len())
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}
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// Variance computes the variance of the buffer.
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func (s Sequence) Variance() float64 {
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if s.Len() == 0 {
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return 0
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}
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m := s.Average()
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var variance, v float64
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for i := 0; i < s.Len(); i++ {
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v = s.GetValue(i)
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variance += (v - m) * (v - m)
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}
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return variance / float64(s.Len())
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}
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// StdDev returns the standard deviation.
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func (s Sequence) StdDev() float64 {
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if s.Len() == 0 {
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return 0
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}
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return math.Pow(s.Variance(), 0.5)
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}
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// Array is a wrapper for an array of floats that implements `ValuesProvider`.
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type Array []float64
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// Len returns the value provider length.
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func (a Array) Len() int {
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return len(a)
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}
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// GetValue returns the value at a given index.
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func (a Array) GetValue(index int) float64 {
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return a[index]
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}
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