按数组内容分组 [英] Group by array contents

问题描述

我有一个List<Tuple<string,long,byte[]>>，我想按字节数组的内容分组.

I have a List<Tuple<string,long,byte[]>> and I want to group by the contents of the byte array.

有没有一种简单的方法可以使用GroupBy和lambda来做到这一点?

Is there a simple way to do this with GroupBy and a lambda?

理想情况下，我希望不创建中间数据结构(例如用于保存数组元素的字符串)来做到这一点.

Ideally, I want to do this without creating an intermediate data structure (like a string to hold the elements of the array).

推荐答案

您可以使用自定义IEqualityComparer<byte[]>(甚至更好的是通用的IEqualityComparer<T[]>)实现来实现:

You can achieve that using custom IEqualityComparer<byte[]> (or even better, generic one: IEqualityComparer<T[]>) implementation:

class ArrayComparer<T> : IEqualityComparer<T[]>
{
    public bool Equals(T[] x, T[] y)
    {
        return x.SequenceEqual(y);
    }

    public int GetHashCode(T[] obj)
    {
        return obj.Aggregate(string.Empty, (s, i) => s + i.GetHashCode(), s => s.GetHashCode());
    }
}

我很确定GetHashCode可以实现得更好，但这只是一个例子！

I'm pretty sure GetHashCode could be implemented much better, but it's just an example!

用法:

var grouped = source.GroupBy(i => i.Item3, new ArrayComparer<byte>())

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