Remove every nth element from swift array

Question

Is there an easy way to remove every nth element from a swift array. For example, in the array below:

thisArray = [2.0, 4.0, 3.0, 1.0, 4.5, 3.3, 1.2, 3.6, 10.3, 4.4, 2.0, 13.0]

If n = 3 and start count from first element would like to return:

returnThis = [2.0, 4.0, 1.0, 4.5, 1.2, 3.6, 4.4, 2.0]

Answer 1

// swift 4.1:
thisArray.enumerated().compactMap { index, element in index % 3 == 2 ? nil : element }

• Use .enumerated() to attach the indices
• Then use .compactMap to filter out items at indices 2, 5, 8, ... by returning nil, and strip the index for the rest by returning just element.

(If you are using Swift 4.0 or below, use .flatMap instead of .compactMap. The .compactMap method was introduced in Swift 4.1 by SE-0187)

(If you are stuck with Swift 2, use .enumerate() instead of .enumerated().)

Answer 2

Since the Functional style solutions have already been posted I am using here an old fashion way approach

let nums = [2.0, 4.0, 3.0, 1.0, 4.5, 3.3, 1.2, 3.6, 10.3, 4.4, 2.0, 13.0]

var filteredNums = [Double]()
for elm in nums.enumerate() where elm.index % 3 != 2 {
    filteredNums.append(elm.element)
}