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42 lines
867 B
Go
42 lines
867 B
Go
package math
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import (
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"math"
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"github.com/MontFerret/ferret/pkg/runtime/core"
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"github.com/MontFerret/ferret/pkg/runtime/values"
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"github.com/MontFerret/ferret/pkg/runtime/values/types"
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)
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func variance(input *values.Array, sample values.Int) values.Float {
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if input.Length() == 0 {
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return values.NewFloat(math.NaN())
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}
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m, _ := mean(input)
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var err error
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var variance values.Float
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input.ForEach(func(value core.Value, idx int) bool {
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err = core.ValidateType(value, types.Int, types.Float)
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if err != nil {
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return false
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}
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n := values.Float(toFloat(value))
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variance += (n - m) * (n - m)
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return true
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})
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// When getting the mean of the squared differences
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// "sample" will allow us to know if it's a sample
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// or population and wether to subtract by one or not
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l := values.Float(input.Length() - (1 * sample))
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return variance / l
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}
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