Question

我有[Int:[String:String]]类型的字典

示例：

[1546696330：[“符号”：“ ETH”，“数量”：“ 1.0”]，1546531017：[“符号”：“ ETH”，“数量”：“ 1.0”]，1546531031：[“符号” ：“ XRP”，“金额”：“ 200.0”]]

如您所见，我有两个重复的字典，键为symbol，值为ETH。我需要删除所有值并保留最小值（整数）的代码。

预期结果：

[1546531017：[“符号”：“ ETH”，“金额”：“ 1.0”]，1546531031：[“符号”：“ XRP”，“金额”：“ 200.0”]]

1546531017 < 1546696330

在哪里

Answer 1

@Larme在评论中描述的算法是解决此问题的直接方法。

创建一个[String:Int]字典，该字典表示要保留的原始字典中的值。键是符号，而 value 是您要保留的Int。

然后使用该字典通过使用keep的值从原始字典中选择条目来构造最终的字典。

代码如下：

// original dictionary
let dict: [Int:[String:String]] = [1546696330: ["symbol": "ETH", "amount": "1.0"], 1546531017: ["symbol": "ETH", "amount": "1.0"], 1546531031: ["symbol": "XRP", "amount": "200.0"]]

// Dictionary mapping symbol to Int of values we want to keep
var keep = [String:Int]()

// Loop on original dictionary deciding on whether to keep this symbol
// based on how its Int compares to the one we've already kept
for (key, value) in dict {
    guard let symbol = value["symbol"] else { continue }
    if let ekey = keep[symbol] {
        // We already have this one, so keep the minimum of the two
        keep[symbol] = min(key, ekey)
    } else {
        keep[symbol] = key
    }
}

// Show the keep dictionary
print(keep)

["XRP": 1546531031, "ETH": 1546531017]

// The final dictionary
var dict2 = [Int:[String:String]]()

// Fill the final dictionary based upon the values we chose to keep
for value in keep.values {
    dict2[value] = dict[value]
}

// Show the final result
print(dict2)

[1546531031: ["amount": "200.0", "symbol": "XRP"], 1546531017: ["amount": "1.0", "symbol": "ETH"]]

使用keep创建reduce(into:)：

如果要使用reduce(into:)创建keep字典来降低可读性，则需要更多Swifty：

let keep: [String:Int] = dict.reduce(into: [:]) {
    guard let symbol = $1.value["symbol"] else { return }
    $0[symbol] = min($0[symbol, default: $1.key], $1.key)
}

使用filter()创建最终字典：

或者，您可以像这样通过过滤原始字典来在一行中创建最终字典：

let dict2 = dict.filter { keep.values.contains($0.key) }

Answer 2

这将删除具有较大int值的重复项

let dict:[Int:[String:String]] = [ 1546531017: ["symbol": "ETH", "amount": "1.0"], 1546531031: ["symbol": "XRP", "amount": "200.0"],1546696330: ["symbol": "ETH", "amount": "1.0"]]
var dict2:[Int:[String:String]] = [:]

dict.forEach({ (key, value) in
    if let item = dict2.first(where: {value["symbol"] == $1["symbol"]}) {
        if (key < item.key) {
            dict2[item.key] = nil
            dict2[key] = value
        }
    } else {
        dict2[key] = value
    }
})

删除字典中的重复项，仅保留最小值

2 个答案: