Swift：如何从双数组中删除重复项？

问题描述

我有一个数组，如 [0.75，0.0050000000000000001，0.0050000000000000001，0.0050000000000000001，0.0050000000000000001，0.0050000000000000001，0.0040000000000000001，...] ，我需要删除重复。我只想集中在小数点后的前3位数字。如何做到这一点？

I have an array of values like [0.75, 0.0050000000000000001, 0.0050000000000000001, 0.0050000000000000001, 0.0050000000000000001, 0.0050000000000000001, 0.0040000000000000001, ...] and I need to remove the duplicates. I only want to focus on the first 3 digits after the decimal point. How do I do this?

推荐答案

您可以使用NumberFormatter修改最小和最大分数数字，并使用set过滤重复元素：

You can use NumberFormatter to fix the minimum and maximum fraction digits and use a set to filter the duplicate elements:

let array = [0.75, 0.0050000000000000001, 0.0050000000000000001, 0.0050000000000000001, 0.0050000000000000001, 0.0050000000000000001, 0.0040000000000000001]

let numberFormatter = NumberFormatter()
numberFormatter.numberStyle = .decimal
numberFormatter.minimumFractionDigits = 3
numberFormatter.maximumFractionDigits = 3

---

---

var set = Set<String>()
let orderedSet: [Double] = array.flatMap {
    guard let string = numberFormatter.string(for: $0) else { return nil }
    return set.insert(string).inserted ? $0 : nil
}

orderedSet   // [0.75, 0.005, 0.004]

如果您需要Strings（由@Hamish建议）：

If you need Strings (as suggested by @Hamish):

var set = Set<String>()
let orderedSet: [String] = array.flatMap {
    guard let string = numberFormatter.string(for: $0) else { return nil }
    return set.insert(string).inserted ? string : nil
}

orderedSet   // ["0.750", "0.005", "0.004"]

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