LINQ:按索引和值分组 [英] LINQ: Group by index and value

问题描述

假设我有一个包含以下值的字符串列表:

Lets say I have an list of strings with the following values:

["a"，"a"，"b"，"a"，"a"，"a"，"c"，"c"]

["a","a","b","a","a","a","c","c"]

我想执行一个linq查询，该查询将分为4组:

I want to execute a linq query that will group into 4 groups:

第1组:["a"，"a"]第2组:["b"]第3组:["a"，"a"，"a"]第4组: ["c"，"c"]

Group 1: ["a","a"] Group 2: ["b"] Group 3: ["a","a","a"] Group 4: ["c","c"]

基本上，我想为值"a"创建2个不同的组，因为它们不是来自同一索引序列".

Basically I want to create 2 different groups for the value "a" because they are not coming from the same "index sequence".

有人为此提供LINQ解决方案吗?

Anyone has a LINQ solution for this?

推荐答案

您只需要键而不是数组项

You just need key other than items of array

var x = new string[] { "a", "a", "a", "b", "a", "a", "c" };


int groupId = -1;
var result = x.Select((s, i) => new
{
    value = s,
    groupId = (i > 0 && x[i - 1] == s) ? groupId : ++groupId
}).GroupBy(u => new { groupId });


foreach (var item in result)
{
    Console.WriteLine(item.Key);
    foreach (var inner in item)
    {
        Console.WriteLine(" => " + inner.value);
    }
}

结果如下:链接

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