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Averages/Mean time of day: Difference between revisions
Add Swift
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</pre>
=={{header|Swift}}==
<lang swift>import Foundation
@inlinable public func d2r<T: FloatingPoint>(_ f: T) -> T { f * .pi / 180 }
@inlinable public func r2d<T: FloatingPoint>(_ f: T) -> T { f * 180 / .pi }
public func meanOfAngles(_ angles: [Double]) -> Double {
let cInv = 1 / Double(angles.count)
let (y, x) =
angles.lazy
.map(d2r)
.map({ (sin($0), cos($0)) })
.reduce(into: (0.0, 0.0), { $0.0 += $1.0; $0.1 += $1.1 })
return r2d(atan2(cInv * y, cInv * x))
}
struct DigitTime {
var hour: Int
var minute: Int
var second: Int
init?(fromString str: String) {
let split = str.components(separatedBy: ":").compactMap(Int.init)
guard split.count == 3 else {
return nil
}
(hour, minute, second) = (split[0], split[1], split[2])
}
init(fromDegrees angle: Double) {
let totalSeconds = 24 * 60 * 60 * angle / 360
second = Int(totalSeconds.truncatingRemainder(dividingBy: 60))
minute = Int((totalSeconds.truncatingRemainder(dividingBy: 3600) - Double(second)) / 60)
hour = Int(totalSeconds / 3600)
}
func toDegrees() -> Double {
return 360 * Double(hour) / 24.0 + 360 * Double(minute) / (24 * 60.0) + 360 * Double(second) / (24 * 3600.0)
}
}
extension DigitTime: CustomStringConvertible {
var description: String { String(format: "%02i:%02i:%02i", hour, minute, second) }
}
let times = ["23:00:17", "23:40:20", "00:12:45", "00:17:19"].compactMap(DigitTime.init(fromString:))
guard times.count == 4 else {
fatalError()
}
let meanTime = DigitTime(fromDegrees: 360 + meanOfAngles(times.map({ $0.toDegrees() })))
print("Given times \(times), the mean time is \(meanTime)")</lang>
{{out}}
<pre>Given times [23:00:17, 23:40:20, 00:12:45, 00:17:19], the mean time is 23:47:43</pre>
=={{header|Tcl}}==
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