CODEWITHSUNDEEP
swiftdictionaryreduce
Torbjørn Kristoffersen
Torbjørn Kristoffersen

Reputation: 808

Map/reduce with index in Swift 4

How would one go about accomplishing something like the following in a more elegant way in Swift 4 e.g using map and/or reduce.

I've simplified the code for the sake of posting here, but note it does require the use of an index.

var numbers = [50, 20, 70, 80, 90]
var result = [0,0,0]
for number in numbers {
  for i in 0...2 {
    result[i] += number + i
  } 
}

The end result should be:

[Int] = 3 values {
  [0] = 310
  [1] = 315
  [2] = 320
}

Upvotes: 5

Views: 3736

Answers (1)

Tomasz Pikć
Tomasz Pikć

Reputation: 763

This is equivalent

let result = (0...2).map({ index in numbers.reduce(0) { (sum, current) in sum + current + index } })

or this if you want to use result array

let r = result.enumerated().map({ (index, _) in numbers.reduce(0) { (sum, current) in sum + current + index } })

but more efficient will be something like that

let sum = numbers.reduce(0, +)
let resultsExpected = 3
let result = (0..<resultsExpected).map({ $0 * numbers.count + sum })

Upvotes: 7

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