I have an array of arrays of Doubles. For example:
let mceGain = [[3,4,5],[7,4,3],[12,10,7]] // Written as integers for simplicity here
//firstAvg: (3+7+12)/3 = 7.33
//secondAvg: (4+4+10)/3 = 6
//thirdAvg: (5+3+7)/3 = 5
//mceGain: [7.33,6,5]
reduce()
map()
filter()
This should answer your comment below
let elms: [[Double]] = [[3, 5, 3], [4, 4, 10] , [5, 3, 7]]
func averageByIndex(elms:[[Double]]) -> [Double]? {
guard let length = elms.first?.count else { return []}
// check all the elements have the same length, otherwise returns nil
guard !elms.contains(where:{ $0.count != length }) else { return nil }
return (0..<length).map { index in
let sum = elms.map { $0[index] }.reduce(0, +)
return sum / Double(elms.count)
}
}
if let averages = averageByIndex(elms: elms) {
print(averages) // [4.0, 4.0, 6.666666666666667]
}