如何在C#中将Lambda表达式作为参数传递 [英] How to pass lambda expressions as parameter in C#

问题描述

我是使用lambda表达式的初学者.

I am beginner at using lambda expressions.

我有一个经销商列表，每个经销商我都必须计算等级.

I have a list of dealers, foreach dealer I have to calculate grade.

要求将成绩计算分为单独的方法.

The request is that the grade calculation to be separated into a separate method.

因此，我正在编写以下两种方法，但是无法将参数传递给 CalculateGrade()方法，

So I am writing the below two methods, however I am unable to pass parameters to CalculateGrade() method,

public IEnumerable<Dealers> GetDealerGrades(IEnumerable<Dealers> gradeData)
{
    return gradeData
        .GroupBy(row => new { row.Name })
        .Select(g => new Dealers
        {
            Name = g.Key.Name,
            TotalPoints = CalculateGrade(x => Convert.ToDouble(x.RecievedPoints),
                                         y => y.MaxPoints,
                                         z => Convert.ToDouble(z.Weightage)) 
        })
        .ToList();
}

private double CalculateGrade(double d1, int d2, double d3)
{
    return ( d1 / d2 ) 
        * d3 == 0.00 ? 1
        : d3;
}

有人可以建议如何在其中传递参数，或者如何传递lamda表达式并计算成绩吗?

Can somebody advise how to pass parameters in this , or how to pass lamda expressions and calculate grade?

非常感谢...

推荐答案

看来您需要:

return gradeData
    .GroupBy(row => row.Name)
    .Select(g => new Dealers
    {
        Name = g.Key.Name,
        TotalPoints = g.Sum(x => CalculateGrade(Convert.ToDouble(x.RecievedPoints),
                                                x.MaxPoints,
                                                Convert.ToDouble(x.Weightage)))
    })
    .ToList();

它将对组中的每个元素调用 CalculateGrade 方法，并将返回的值求和到 TotalPoints 属性中.

It will call CalculateGrade method on every element from group and sum returned values into TotalPoints property.

或者您可以更改您的 CalculateGrade 以采用 IEnumerabale<经销商> :

Or you can change your CalculateGrade to take IEnumerabale<Dealers>:

private double CalculateGrade(IEnumerable<Dealers> dealers)
{
    // calculations here
    return dealers.Sum(x => CalculateGrade(Convert.ToDouble(x.RecievedPoints),
                                            x.MaxPoints,
                                            Convert.ToDouble(x.Weightage)))
}

并在查询中使用它:

return gradeData
    .GroupBy(row => row.Name)
    .Select(g => new Dealers
    {
        Name = g.Key.Name,
        TotalPoints = CalculateGrade(g)
    })
    .ToList();

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