使用LINQ规范化数据
假设我们有一些非规范化数据,如下所示:使用LINQ规范化数据,linq,normalization,Linq,Normalization,假设我们有一些非规范化数据,如下所示: List<string[]> dataSource = new List<string[]>(); string [] row1 = {"grandParentTitle1", "parentTitle1", "childTitle1"}; string [] row2 = {"grandParentTitle1", "parentTitle1", "childTitle2"}; string [] row3 = {"grandP
List<string[]> dataSource = new List<string[]>();
string [] row1 = {"grandParentTitle1", "parentTitle1", "childTitle1"};
string [] row2 = {"grandParentTitle1", "parentTitle1", "childTitle2"};
string [] row3 = {"grandParentTitle1", "parentTitle2", "childTitle3"};
string [] row4 = {"grandParentTitle1", "parentTitle2", "childTitle4"};
dataSource.Add(row1);
List dataSource=newlist();
字符串[]行1={“祖父母标题1”、“父母标题1”、“子女标题1”};
字符串[]行2={“祖父母标题1”、“父母标题1”、“子女标题2”};
字符串[]行3={“祖父母标题1”、“父母标题2”、“子女标题3”};
字符串[]行4={“祖父母标题1”、“父母标题2”、“子女标题4”};
dataSource.Add(第1行);
我需要对其进行规范化,例如,使用Child.Parent和Child.Parent.祖父母填充IEnumerable请给出一个提示,这可以通过功能性的方式实现吗?Linq确实做了与此相反的事情。如果你把它正常化了,你可以很容易地说
from g in grandParents
from p in g.Parents
from c in p.Children
select new { GrandParentName = g.Name, ParentName = p.Name, ChildName = c.Name };
按照你的要求去做更棘手。像这样的
var grandparents = (from g in dataSource
select new GrandParent {
Title = g[0],
Parents = (from p in dataSource
where p[0] == g[0]
select new Parent {
Title = p[1],
Children = from c in dataSource
where p[1] == c[1]
select new
{
Title = c[2]
}
}).Distinct(new ParentTitleComparer())
}).Distinct(new GrandParentTitleComparer());
我不认为这比命令式版本读起来更好。最基本的方法是使用匿名变量:
from ds0 in dataSource group ds0 by ds0[0] into grandparents
select new
{
Grandparent = grandparents.Key,
Parents =
from ds1 in grandparents group ds1 by ds1[1] into parents
select new
{
Parent = parents.Key,
Children = from ds2 in parents select ds2[2]
}
};
如果你想用具体的类来实现这一点,我建议你创建一个Person
类,这个类的构造函数采用一个IEnumerable
来表示被构造的Person
的子类。然后你可以这样做:
from ds0 in dataSource
group ds0 by ds0[0] into grandparents
select new Person(grandparents.Key,
from ds1 in grandparents
group ds1 by ds1[1] into parents
select new Person(parents.Key,
from ds2 in parents
select new Person(ds2[2])));
这两种解决方案中有一种适合您吗
如果您想要不同的
祖父母
,父母
和子女
类型,那么您应该能够修改最后一个示例以适应。您可以使用group by准确地执行您想要的操作。不幸的是,我对C#LINQ语法的了解有限,所以我只能向您展示调用扩展方法GroupBy的方法
var normalized = dataSource
.GroupBy(source => source[0], (grandParent, grandParentChilds) => new { GrandParent = grandParent, Parents = grandParentChilds
.GroupBy(source => source[1], (parent, parentChilds) => new { Parent = parent, Children = from source in parentChilds select source[2]}) });
foreach (var grandParent in normalized)
{
Console.WriteLine("GrandParent: {0}", grandParent.GrandParent);
foreach (var parent in grandParent.Parents)
{
Console.WriteLine("\tParent: {0}", parent.Parent);
foreach (string child in parent.Children)
Console.WriteLine("\t\tChild: {0}", child);
}
}
问题是如何创建和链接实体,而不使用重复项。选择(新父母{祖父母=新祖父母}),否则我会错过什么?