find the variance of all values in a map in go

main.go
package main

import (
	"fmt"
	"math"
)

func variance(m map[int]float64) float64 {
	// Step 1: Calculate the mean value
	var sum float64
	for _, v := range m {
		sum += v
	}
	mean := sum / float64(len(m))

	// Step 2: Calculate the difference between each value and the mean, square it, and add it to a sum
	var sqDiffSum float64
	for _, v := range m {
		diff := v - mean
		sqDiffSum += math.Pow(diff, 2)
	}

	// Step 3: Divide the sum by the number of values in the map to get the variance
	variance := sqDiffSum / float64(len(m))

	return variance
}

func main() {
	// Example usage
	m := map[int]float64{1: 2, 2: 4, 3: 6, 4: 8, 5: 10}
	result := variance(m)
	fmt.Println(result) // Output: 8
}
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