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jonelf/standard_deviation.swift

Last active February 15, 2024 21:45
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Standard Deviation in Swift
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standard_deviation.swift
func standardDeviation(arr : [Double]) -> Double
{
let length = Double(arr.count)
let avg = arr.reduce(0, {$0 + $1}) / length
let sumOfSquaredAvgDiff = arr.map { pow($0 - avg, 2.0)}.reduce(0, {$0 + $1})
return sqrt(sumOfSquaredAvgDiff / length)
}
let responseTimes = [ 18.0, 21.0, 41.0, 42.0, 48.0, 50.0, 55.0, 90.0 ]
standardDeviation(responseTimes) // 20.8742514835862
standardDeviation([2,4,4,4,5,5,7,9]) // 2.0
@sbromberger
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also, I think .reduce(0, {$0 + $1}) can be simplified to .reduce(0, +).

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