组和求和与选择许多c#
本文关键字:许多 选择 求和 | 更新日期: 2023-09-27 18:12:41
我有一个传入数组,每行有一个计数和一个字符串,它代表一个或多个键的下划线分割。
我想对每个键进行分组和求和,如果键出现在一行中,总数为5,则被下划线分割的每个项的总数增加5。
我只是想知道这将如何表示在linq…
class Owl
{
public int SpeciesCount { get; set; }
public string BandIdentifier { get; set; }
}
public class GoOwl
{
public GoOwl(Owl[] owls)
{
//just making a list of test data to illustrate what would be coming in on the array
var owlList = new List<Owl>();
owlList.Add(new Owl { SpeciesCount = 2, BandIdentifier = "OWL1" });
owlList.Add(new Owl { SpeciesCount = 1, BandIdentifier = "OWL1_OWL2_OWL3" });
owlList.Add(new Owl { SpeciesCount = 2, BandIdentifier = "OWL3" });
owlList.Add(new Owl { SpeciesCount = 5, BandIdentifier = "OWL2_OWL3" });
//i'd ideally like to have something like a row for each band identifier split on underscore plus a total species count..
//where you'd sum the species count for each underscored item and group
}
}
下面将是作为单个Owl对象的期望输出
["OWL1", 3]
["OWL2", 6]
["OWL3", 8]
我仍然没有得到SelectMany..
欢呼
在fluent sytnax中:
//For each 'owlItem' in the owlList, select an anonymous objects for each key in the BandIdentifier string, keeping track of the associated SpeciesCount
//Since each call to Split('_').Select(...) produces an IEnumerable of those anonymous objects, use SelectMany to flatten the IEnumerable to IEnumerables
owlList.SelectMany(owlItem => owlItem.BandIdentifier.Split('_')
.Select(key => new { OwlKey = key, owlItem.SpeciesCount }))
//Group together those anonymous objects if they share the same key
.GroupBy(info => info.OwlKey)
//For each of the groups, sum together all the associated SpeciesCounts
.Select(group => new { group.Key, SpeciesCount = group.Sum(info => info.SpeciesCount) })'
你似乎想要这个:
var results =
owlList.SelectMany(owl => owl.BandIdentifier.Split('_'),
(owl, band) => new { owl, band })
.GroupBy(x => x.band)
.Select(group => new Owl
{
BandIdentifier = group.Key
SpeciesCount = group.Sum(g => g.SpeciesCount)
});
或者在查询语法中:
var results =
from owl in owlList
from band in owl.BandIdentifier.Split('_')
group owl by band into group
select new Owl {
BandIdentifier = group.Key
SpeciesCount = group.Sum(g => g.SpeciesCount)
};
var owlResults = owlList
//Use SelectMany to split and select all species
//and have a select to get the count along with the species
.SelectMany(O => O.BandIdentifier.Split('_')
.Select(owl => new { Species = owl, Count = O.SpeciesCount }))
//Here you can group and get the sum
.GroupBy(O => O.Species)
.Select(owl => new { Species = owl.Key, Count = owl.Sum(o => o.Count) });