在Swift中有没有对应的Scala、Xtend、Groovy、Ruby等等?
var aofa = [[1,2,3],[4],[5,6,7,8,9]]
aofa.flatten() // shall deliver [1,2,3,4,5,6,7,8,9]
当然我可以用reduce来做，但那有点糟糕
var flattened = aofa.reduce(Int[]()){
a,i in var b : Int[] = a
b.extend(i)
return b
}
当前回答
修改了@RahmiBozdag的回答， 1. 公共扩展中的方法是公共的。 2. 删除了额外的方法，因为开始索引将始终为零。 3.我没有找到一种方法把compactMap内部为nil和可选的，因为内部方法T总是[Any?]，欢迎提出任何建议。
let array = [[[1, 2, 3], 4], 5, [6, [9], 10], 11, nil] as [Any?]
public extension Array {
func flatten<T>(_ index: Int = 0) -> [T] {
guard index < self.count else {
return []
}
var flatten: [T] = []
if let itemArr = self[index] as? [T] {
flatten += itemArr.flatten()
} else if let element = self[index] as? T {
flatten.append(element)
}
return flatten + self.flatten(index + 1)
}
}
let result: [Any] = array.flatten().compactMap { $0 }
print(result)
//[1, 2, 3, 4, 5, 6, 9, 10, 11]
其他回答
struct Group {
var members: [String]?
}
let groups = [Group]()
let outputMembers: [String] = Array(groups.compactMap({ $0.members }).joined())
描述
如果要制作单数组的数组对象模型。示例:我们从所有组中获取outputMembers单个数组。
Swift >= 3.0
减少:
let numbers = [[1,2,3],[4],[5,6,7,8,9]]
let reduced = numbers.reduce([], +)
flatMap:
let numbers = [[1,2,3],[4],[5,6,7,8,9]]
let flattened = numbers.flatMap { $0 }
加入:
let numbers = [[1,2,3],[4],[5,6,7,8,9]]
let joined = Array(numbers.joined())
你可以用下面的方法来平嵌套数组:
var arrays = [1, 2, 3, 4, 5, [12, 22, 32], [[1, 2, 3], 1, 3, 4, [[[777, 888, 8999]]]]] as [Any]
func flatten(_ array: [Any]) -> [Any] {
return array.reduce([Any]()) { result, current in
switch current {
case(let arrayOfAny as [Any]):
return result + flatten(arrayOfAny)
default:
return result + [current]
}
}
}
let result = flatten(arrays)
print(result)
/// [1, 2, 3, 4, 5, 12, 22, 32, 1, 2, 3, 1, 3, 4, 777, 888, 8999]
func convert(){
let arr = [[1,2,3],[4],[5,6,7,8,9]]
print("Old Arr = ",arr)
var newArr = [Int]()
for i in arr{
for j in i{
newArr.append(j)
}
}
print("New Arr = ",newArr)
}
flatten()在Swift 3中根据SE-0133重命名为joined():
https://github.com/apple/swift-evolution/blob/master/proposals/0133-rename-flatten-to-joined.md
