如何对集合中连续的相似项目进行分组? [英] How to group consecutive similar items of a collection?

问题描述

请考虑以下集合.

• 真
• 错误
• 错误
• 错误
• 真
• 真
• 错误
• 错误

我想以结构化的方式显示它，例如，以TreeView形式显示.我希望能够在整个组等周围绘制边框.

I want to display it in a structured way, say, in a TreeView. I want to be able to draw borders around entire groups and such.

• 真实小组
  • 真
  • True Group
    • True
    • 错误
    • 错误
    • 错误
    • 真
    • 真
    • 错误
    • 错误

    如何用尽可能少的过程代码来完成此操作?

    How do I accomplish this with as little procedural code as possible?

    推荐答案

    这可以满足您的需求，并且通用:

    This does what you're looking for and is generic:

    private static IEnumerable<IGrouping<int, T>> GroupConsecutive<T>(this IEnumerable<T> set, Func<T, T, bool> predicate)
    {
        var i = 0;
        var k = 0;
        var ranges = from e in set
                     let idx = ++i
                     let next = set.ElementAtOrDefault(idx)
                     let key = (predicate(e, next)) ? k : k++
                     group e by key into g
                     select g;
        return ranges;
    }
    

    用法:

    var set = new List<bool>
                {
                    true,
                    false,
                    false,
                    false,
                    true,
                    true,
                    false,
                    false,
                };
    var groups = set.GroupConsecutive((b1, b2) => (b1 == b2));
    foreach (var g in groups)
    {
        Console.WriteLine(g.Key);
        foreach (var b in g)
            Console.WriteLine("\t{0}", b);
    }
    

    输出:

    0
            True
    1
            False
            False
            False
    2
            True
            True
    3
            False
            False
    

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