分组为连续整数范围

Question

我已经使用Linq检查了其他帖子,包括Group by variable integer range

但我没有发现任何类似于我的问题...我试图分组整数范围,其中整数序列是不连续的.例如,如果我有一组来自1-100的连续整数然后我的设置跳过101,我想创建一条记录从记录#1和#100获取日期,其中记录#1的日期是开始日期,#100是结束日期.

每个连续整数范围都会创建一个新记录,以添加到记录列表中,以指示范围开始和结束时的日期.如果范围仅包含一个整数值(例如,整数范围从1-100,102和104-200),则单个整数范围将具有相同的开始和结束日期.

有什么建议？

Answer 1

您可以创建一个扩展方法来执行此操作:

static class EnumerableIntExtensions {
    public static IEnumerable<IEnumerable<T>> ToContiguousSequences<T>(
        this IEnumerable<T> sequence,
        Func<T, T> next
    ) {
        Contract.Requires(sequence != null);
        Contract.Requires(next != null);
        var e = sequence.GetEnumerator();
        if (!e.MoveNext()) {
            throw new InvalidOperationException("Sequence is empty.");
        }
        var currentList = new List<T> { e.Current };
        while (e.MoveNext()) {
            T current = e.Current;
            if (current.Equals(next(currentList.Last()))) {
                currentList.Add(current);
            }
            else {
                yield return currentList;
                currentList = new List<T> { current };
            }
        }
        yield return currentList;
    }
}

用法:

var sequence = Enumerable.Range(1, 100)
                         .Concat(new[] { 102 })
                         .Concat(Enumerable.Range(104, 97));
var sequences = sequence.ToContiguousSequences(n => n + 1);
foreach(var contiguousSequence in sequences) {
    Console.WriteLine(String.Join(", ", contiguousSequence.Select(n => n.ToString())));
}

输出:

1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81, 82, 83, 84, 85, 86, 87, 88, 89, 90, 91, 92, 93, 94, 95, 96, 97, 98, 99, 100
102
104, 105, 106, 107, 108, 109, 110, 111, 112, 113, 114, 115, 116, 117, 118, 119, 120, 121, 122, 123, 124, 125, 126, 127, 128, 129, 130, 131, 132, 133, 134, 135, 136, 137, 138, 139, 140, 141, 142, 143, 144, 145, 146, 147, 148, 149, 150, 151, 152, 153, 154, 155, 156, 157, 158, 159, 160, 161, 162, 163, 164, 165, 166, 167, 168, 169, 170, 171, 172, 173, 174, 175, 176, 177, 178, 179, 180, 181, 182, 183, 184, 185, 186, 187, 188, 189, 190, 191, 192, 193, 194, 195, 196, 197, 198, 199, 200