C# 合并两个 IEnumerable<T>
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Merging two IEnumerable<T>s
提问by Boris Callens
I have two IEnumerable<T>s.
我有两个IEnumerable<T>。
One gets filled with the fallback ellements. This one will always contain the most elements. The other one will get filled depending on some parameters and will possibly contain less elements. If an element doesn't exist in the second one, I need to fill it with the equivalent one of the first one.
一个充满了后备元素。这将始终包含最多的元素。另一个将根据某些参数被填充，并且可能包含更少的元素。如果第二个元素中不存在元素，我需要用第一个元素的等效元素填充它。
This code does the job, but feels inefficient to me and requires me to cast the IEnumerables to ILists or to use a temporary list Person implements IEquatable
这段代码完成了这项工作，但对我来说效率低下，需要我将 IEnumerables 转换为 ILists 或使用临时列表 Person 实现 IEquatable
IEnumerable<Person> fallBack = Repository.GetPersons();
IList<Person> translated = Repository.GetPersons(language).ToList();
foreach (Person person in fallBack)
{
if (!translated.Any(p=>p.equals(person)))
translated.add(person);
}
Any suggestions?
有什么建议？
采纳答案by JaredPar
Try this.
尝试这个。
public static IEnumerable<Person> SmartCombine(IEnumerable<Person> fallback, IEnumerable<Person> translated) {
return translated.Concat(fallback.Where(p => !translated.Any(x => x.id.equals(p.id)));
}
回答by Jon Skeet
translated.Union(fallback)
or (if Person doesn't implement IEquatable<Person>by ID)
或（如果 Person 没有IEquatable<Person>通过 ID实现）
translated.Union(fallback, PersonComparer.Instance)
where PersonComparer is:
其中 PersonComparer 是：
public class PersonComparer : IEqualityComparer<Person>
{
public static readonly PersonComparer Instance = new PersonComparer();
// We don't need any more instances
private PersonComparer() {}
public int GetHashCode(Person p)
{
return p.id;
}
public bool Equals(Person p1, Person p2)
{
if (Object.ReferenceEquals(p1, p2))
{
return true;
}
if (Object.ReferenceEquals(p1, null) ||
Object.ReferenceEquals(p2, null))
{
return false;
}
return p1.id == p2.id;
}
}
回答by smenon
use Concat. Uniondoes not work in case List<dynamic>type
使用Concat. Union在 caseList<dynamic>类型中不起作用
