mirror of
https://github.com/MontFerret/ferret.git
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88 lines
2.2 KiB
Go
88 lines
2.2 KiB
Go
package math
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import (
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"context"
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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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"github.com/pkg/errors"
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)
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// Percentile returns the nth percentile of the values in a given array.
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// @param array (Array) - Array of numbers.
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// @param numb (Int) - A number which must be between 0 (excluded) and 100 (included).
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// @param method (String, optional) - "rank" (default) or "interpolation".
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// @returns (Float) - The nth percentile, or null if the array is empty or only null values are contained in it or the percentile cannot be calculated.
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func Percentile(_ context.Context, args ...core.Value) (core.Value, error) {
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err := core.ValidateArgs(args, 2, 3)
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if err != nil {
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return values.None, err
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}
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err = core.ValidateType(args[0], types.Array)
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if err != nil {
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return values.None, err
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}
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err = core.ValidateType(args[1], types.Int)
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if err != nil {
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return values.None, err
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}
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// TODO: Implement different methods
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//method := "rank"
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//
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//if len(args) > 2 {
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// err = core.ValidateType(args[2], core.StringType)
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//
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// if err != nil {
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// return values.None, err
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// }
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//
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// if args[2].String() == "interpolation" {
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// method = "interpolation"
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// }
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//}
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arr := args[0].(*values.Array)
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percent := values.Float(args[1].(values.Int))
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if arr.Length() == 0 {
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return values.NewFloat(math.NaN()), nil
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}
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if percent <= 0 || percent > 100 {
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return values.NewFloat(math.NaN()), errors.New("input is outside of range")
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}
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sorted := arr.Sort()
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// Multiply percent by length of input
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l := values.Float(sorted.Length())
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index := (percent / 100) * l
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even := values.Float(values.Int(index))
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var percentile core.Value
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// Check if the index is a whole number
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switch {
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case index == even:
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i := values.Int(index)
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percentile = sorted.Get(i - 1)
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case index > 1:
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// Convert float to int via truncation
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i := values.Int(index)
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// Find the average of the index and following values
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percentile, _ = mean(values.NewArrayWith(sorted.Get(i-1), sorted.Get(i)))
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default:
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return values.NewFloat(math.NaN()), errors.New("input is outside of range")
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}
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return percentile, nil
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}
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