Are there any standard library calls I can use to either perform set operations on two arrays, or implement such logic myself (ideally as functionally and also efficiently as possible)?
Difference between an Array and Set in SwiftArray is faster than set in terms of initialization.
Internally, A set in Swift uses a hash table to store elements in the set. Let us consider an example, we want to check the number of unique or different marks scored by students in a class. A set can be used to accomplish this task. Let a list containing marks be, list = [98, 80, 86, 80, 98, 98, 67, 90, 67, 84].
Swift provides three primary collection types, known as arrays, sets, and dictionaries, for storing collections of values. Arrays are ordered collections of values. Sets are unordered collections of unique values.
Swift makes it as easy to create a new set as to create a new array. Simply assign an array literal to a variable or constant with the Set type specified. let ingredients: Set = ["cocoa beans", "sugar", "cocoa butter", "salt"] if ingredients.
Yes, Swift has the Set
class.
let array1 = ["a", "b", "c"] let array2 = ["a", "b", "d"] let set1:Set<String> = Set(array1) let set2:Set<String> = Set(array2)
Swift 3.0+ can do operations on sets as:
firstSet.union(secondSet)// Union of two sets firstSet.intersection(secondSet)// Intersection of two sets firstSet.symmetricDifference(secondSet)// exclusiveOr
Swift 2.0 can calculate on array arguments:
set1.union(array2) // {"a", "b", "c", "d"} set1.intersect(array2) // {"a", "b"} set1.subtract(array2) // {"c"} set1.exclusiveOr(array2) // {"c", "d"}
Swift 1.2+ can calculate on sets:
set1.union(set2) // {"a", "b", "c", "d"} set1.intersect(set2) // {"a", "b"} set1.subtract(set2) // {"c"} set1.exclusiveOr(set2) // {"c", "d"}
If you're using custom structs, you need to implement Hashable.
Thanks to Michael Stern in the comments for the Swift 2.0 update.
Thanks to Amjad Husseini in the comments for the Hashable info.
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