Question

我在我的方法中创建一个委托Func，以检查 schedualCode 是否适合列表中的某个位置，其中限制为3。我想在列表中计算schedualCode的不同值。我的问题是schedualCodeCount返回1.它应该返回2。这是我的代码

        Func<string, bool> CheckTimeLimit = delegate (string schedualCode)
        {
            // check enrolled period count (where limit is 3) 
            //int periodCount = currentEnrollments.GroupBy(t => t.Times)
            //.Select(t => t.Key.Select(key => key.PeriodCode == time.PeriodCode).Distinct()).Count();
            var allTimes = currentEnrollments.SelectMany(key => key.Times).ToList();

            List<string> schedualCodes = allTimes.Where(key => key.SchedualCode == schedualCode && key.ViewOnSchedual)
                                                 .Select(key => key.SchedualCode).ToList();

            //schedualCodes List returns a list of count = 2 , and 2 strings exactly the same of value  = "A1"


            // Getting the distinct count of "A1"
            int schedualCodeCount = schedualCodes.Distinct().Count();
            // schedualCodeCount gets the value = 1, where it should be 2 

            // time fits if true
            return schedualCodeCount < 3;
        };

Answer 1

你误解了Distinct的作用。你有两个相同的项目，区别将删除你留下的重复项1.您可能想要做的是分组，然后得到每个组的计数。

例如：

var list = new List<string>() { "A1", "A1" };

Console.WriteLine(list.Count);         // 2, obviously

var distinct = list.Distinct();        // select only the *distinct* values
Console.WriteLine(distinct.Count());   // 1 - because there is only 1 distinct value

var groups = list.GroupBy(s => s);     // group your list (there will only be one
                                       // in this case)

foreach (var g in groups)              // for each group
{
    // Display the number of items with the same key
    Console.WriteLine(g.Key + ":" + g.Count());   
}

LINQ Distinct Count返回1

1 个答案: