Question

我有Tuple<string, int>的列表：

"dog", 25
"cat", 5
"cat", 7
"rat", 4
"dog", 10

我需要的Linq查询规则必须满足以下条件：我需要按字符串值对元组进行分组，但仅限于至少出现2次。分组元素的聚合应该是乘法。毕竟我需要聚合元素的总和。在上面的例子中，结果是25 * 10 + 5 * 7 = 285。

到目前为止，我已经尝试过其他几件事：

var query = from tuple in firstTupleList.Concat(secondTupleList)
                            group tuple.Item2 by tuple.Item1 into g
                            select Tuple.Create(g.Key, g.Aggregate((x, y) => x * y));

这是狗和猫的乘法，但是老鼠仍然在列表中是错误的。

Answer 1

你应该可以这样做：

var grouped = list.GroupBy(t => t.Item1)
              .Where(g => g.Count() > 1)
              .Select(g => Tuple.Create(g.Key, g.Skip(1).Aggregate(g.First().Item2, (i,j) => i*j.Item2)))
              .ToList();

var total = grouped.Sum(i => i.Item2);

Answer 2

你走了：

    List<Tuple<string, int>> list = new List<Tuple<string, int>>();
    list.Add(Tuple.Create<string, int>("dog", 25));
    list.Add(Tuple.Create<string, int>("dog", 10));
    list.Add(Tuple.Create<string, int>("cat", 5));
    list.Add(Tuple.Create<string, int>("cat", 7));
    list.Add(Tuple.Create<string, int>("other", 4));

    Dictionary<string, int> dic = list.
     GroupBy(t => t.Item1).
     Where(grp => grp.Count() > 1).
     ToDictionary(grp => grp.Key,
                  grp => grp.Select(tuple => tuple.Item2).Aggregate((a, b) => a * b));

列表中元组的总数，总和和乘积

2 个答案: