arrays – Array包含一个完整的子数组

发布时间：2020-12-14 05:01:22 所属栏目：百科来源：网络整理

导读：在 Swift中,如何检查数组是否包含完整的给定子数组？例如,是否有一个包含这样的函数： let mainArray = ["hello","world","it's","a","beautiful","day"]contains(mainArray,["world","it's"]) // would return truecontains(mainArray,"it"]) // would retu

在 Swift中,如何检查数组是否包含完整的给定子数组？例如,是否有一个包含这样的函数：

let mainArray = ["hello","world","it's","a","beautiful","day"]
contains(mainArray,["world","it's"])   // would return true
contains(mainArray,"it"])   // would return false
contains(mainArray,"a"])   // would return false - not adjacent in mainArray

解决方法

您可以使用更高级别的功能来执行此操作,如下所示：

func indexOf(data:[String],_ part:[String]) -> Int? {
    // This is to prevent construction of a range from zero to negative
    if part.count > data.count {
        return nil
    }

    // The index of the match could not exceed data.count-part.count
    return (0...data.count-part.count).indexOf {ind in
        // Construct a sub-array from current index,// and compare its content to what we are looking for.
        [String](data[ind..<ind+part.count]) == part
    }
}

此函数返回第一个匹配的索引(如果有),否则返回nil.

您可以按如下方式使用它：

let mainArray = ["hello","day"]
if let index = indexOf(mainArray,"it's"]) {
    print("Found match at (index)")
} else {
    print("No match")
}

编辑为通用数组的扩展…

现在可以将其用于Equatable类型的任何同类数组.

extension Array where Element : Equatable {
    func indexOfContiguous(subArray:[Element]) -> Int? {

        // This is to prevent construction of a range from zero to negative
        if subArray.count > self.count {
            return nil
        }

        // The index of the match could not exceed data.count-part.count
        return (0...self.count-subArray.count).indexOf { ind in
            // Construct a sub-array from current index,// and compare its content to what we are looking for.
            [Element](self[ind..<ind+subArray.count]) == subArray
        }
    }
}

（编辑：李大同）

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