Question

我正在尝试获取数组字典中的最大值，我还需要获取该数组的键。

这就是我得到最大值的方式：

let interestingNumbers = [
    "Prime": [2, 3, 5, 7, 11, 13],
    "Fibonacci": [1, 1, 2, 3, 5, 8],
    "Square": [1, 4, 9, 16, 25]
]
var largest = 0

for (kind, numbers) in interestingNumbers {
    for number in numbers {
        if number > largest {
            largest = number
        }
    }
}

Answer 1

你可以使用Swift功能。

let interestingNumbers = [
    "Prime": [2, 3, 5, 7, 11, 13],
    "Fibonacci": [1, 1, 2, 3, 5, 8],
    "Square": [1, 4, 9, 16, 25],
    ]

if let value = interestingNumbers.map ({ ($0, $1.max() ?? 0) }).max(by: { $0.1 < $1.1 }) {
    print(value.0, value.1) // Square 25
}

让我们一步一步走

首先，我创建了tuple类型为[(String, Int)]的数组，第一个位置它将存储组，第二个位置它将存储相应数组的最大值。

let array = interestingNumbers.map ({ ($0, $1.max() ?? 0) })
//[("Fibonacci", 8), ("Square", 25), ("Prime", 13)]

现在从元组数组中找到最大Int。

if let value = array.max(by: { $0.1 < $1.1 }) {
    print(value.0, value.1) //Will print group here it is "Square 25"
}

Answer 2

我会在字典值中使用max方法，并从生成的元组值中获取最大值：

if let result = interestingNumbers.max(by: {$0.value.max() ?? 0 < $1.value.max() ?? 0}),
    let maxValue = result.value.max() {
    print(result.key)    // "Square\n"
    print(result.value)  // "[1, 4, 9, 16, 25]\n"
    print(maxValue)      // 25
}

Answer 3

let interestingNumbers = [
    "Prime": [2, 3, 5, 7, 11, 13],
    "Fibonacci": [1, 1, 2, 3, 5, 8],
    "Square": [1, 4, 9, 16, 25],
]
var largest = 0
var largest_kind : String? =nil
for (kind, numbers) in interestingNumbers {
    for number in numbers {
        if number > largest {
            largest = number
            largest_kind = kind
        }
    }
}

Answer 4

为什么不使用元组来保持最大值？

let interestingNumbers = [
    "Prime": [2, 3, 5, 7, 11, 13],
    "Fibonacci": [1, 1, 2, 3, 5, 8],
    "Square": [1, 4, 9, 16, 25],
]

var largest: (kind: String?, number: Int) = (nil, 0)

for (kind, numbers) in interestingNumbers {
    for number in numbers {
        if number > largest.number {
            largest = (kind, number)
        }
    }
}

可以进一步简化为：

var largest: (kind: String?, number: Int) = (nil, 0)

for (kind, numbers) in interestingNumbers {
    let max = numbers.max() ?? 0
    if max > largest.number {
        largest = (kind, max)
    }
}

另一种方法是首先将值展平为(kind, number)序列：

let flattened = interestingNumbers
    .map { (kind, numbers) in numbers.map { (kind, $0) } }
    .joined()

let largest = flattened.max(by: { $0.1 < $1.1} )
print(largest)

或者您可以意识到只有每个数组中的最大值才是最重要的，因此：

let largestPerKind = interestingNumbers
    .map { (kind, numbers) in (kind, numbers.max() ?? 0) }

let largest = largestPerKind.max(by: { $0.1 < $1.1} )
print(largest)

如何从数组字典中的整数数组中获取最大值

4 个答案: