IQR Method Claude.ai in Go

main.go

package main

import (
	"fmt"
	"math"
	"sort"
)

// RemoveOutliers removes outliers from a slice of prices using the IQR method
// multiplier is typically 1.5 for mild outlier detection or 3 for extreme outliers
func RemoveOutliers(prices []float64, multiplier float64) []float64 {
	if len(prices) <= 3 {
		return prices // Not enough data to determine outliers
	}

	// Create a copy of the prices to avoid modifying the original
	sortedPrices := make([]float64, len(prices))
	copy(sortedPrices, prices)

	// Sort the array
	sort.Float64s(sortedPrices)

	// Calculate quartile positions
	q1Pos := int(math.Floor(float64(len(sortedPrices)) * 0.25))
	q3Pos := int(math.Floor(float64(len(sortedPrices)) * 0.75))

	// Get quartile values
	q1 := sortedPrices[q1Pos]
	q3 := sortedPrices[q3Pos]

	// Calculate IQR (Interquartile Range)
	iqr := q3 - q1

	// Define bounds for outliers
	lowerBound := q1 - (multiplier * iqr)
	upperBound := q3 + (multiplier * iqr)

	// Filter out the outliers
	result := []float64{}
	for _, price := range prices {
		if price >= lowerBound && price <= upperBound {
			result = append(result, price)
		}
	}

	return result
}

// Usage example
func main() {
	prices := []float64{10.5, 11.2, 12.0, 12.3, 12.5, 12.7, 13.0, 13.5, 50.0, 100.0, 2.0}
	filteredPrices := RemoveOutliers(prices, 1.5)

	fmt.Println("Unfiltered", prices)
	// 10.5 11.2 12 12.3 12.5 12.7 13 13.5 50 100 2]
	// filteredPrices now contains the prices with outliers removed
	fmt.Println("Filtered", filteredPrices)
	// [10.5 11.2 12 12.3 12.5 12.7 13 13.5]
}