使用LINQ和lambdas搜索Dictionary> Class> List>结构数据 [英] Using LINQ and lambdas to search Dictionary>Class>List>Struct data

问题描述

提供了以下数据源:

public struct Strc
{
    public decimal A;
    public decimal B;
    // more stuff
}

public class CLASS
{
    public List<Strc> listStrc = new  List<Strc>();
    // other stuff
}

Dictionary<string, CLASS> dict = new Dictionary<string, CLASS>();

我需要收集字典中的所有Strc.B，前提是Strc.A例如> 3.

I need to collect all the Strc.B in the dictionary, provided Strc.A is e.g > 3.

我得到以下结果:

List<decimal> results = (
    from v in dizS.Values
    from ls in v.listStr
    where ls.A > 3
    select ls.B
    ).ToList();

我也在尝试使用lambdas编写它，但是我失败了...

I was also trying to write it using lambdas, but I fail miserably...

var res = dict.Values.Where(x => x.listStrc.Any(z => z.A > 3))

这是我所能获得的，但是我没有设法选择.B数据... 我做错了什么? (考虑到我一开始就正确地采取了任何措施:D) 谢谢您的宝贵时间.

this is as far as I could get, but I do not manage to select then the .B data... What do I do wrong? (given I did anything right in the first place :D) Thanks for your time.

推荐答案

您实际上是将展平为一系列的struct值-展平用SelectMany表示.所以你想要:

You're essentially flattening to a sequence of the struct values - and that flattening is represented with SelectMany. So you want:

var res = dict.Values
    .SelectMany(x => x.listSrc)
    .Where(ls => ls.A > 3)
    .Select(ls => ls.B);

这基本上等同于您的查询表达式，但是您尝试的方法调用建议尝试获得不同的结果，如果>项中的 any 的A值大于3，您希望从该listSrc的所有B值中的 all .希望前者是您真正想要的，但值得仔细考虑.

This is basically equivalent to your query expression, but your attempted method calls suggest trying to get a different result, where if any of the entries of listSrc have an A value greater than 3, you'd want all of the B values from that listSrc. Hopefully the former is what you really want, but it's worth thinking about that carefully.

这篇关于使用LINQ和lambdas搜索Dictionary> Class> List>结构数据的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！