比较两个对象时,有条件地更改GetHashCode()
本文关键字:有条件 GetHashCode 对象 两个 比较 | 更新日期: 2023-09-27 17:54:32
我有两个不同的对象列表,希望根据某些属性的权重获得它们的相似性。最快的方法似乎是实现一个公平的接口,这就是我所做的:
public class CompareEntry : IEquatable<CompareEntry>
{
public int LeadId { get; set; }
public int SaleId { get; set; }
public string Email { get; set; }
public string PhonePrivate { get; set; }
public string PhoneMobile { get; set; }
public string PhoneCompany { get; set; }
public string FirstName { get; set; }
public string Name { get; set; }
public string City { get; set; }
public string ZipCode { get; set; }
public string CompanyName { get; set; }
public bool Equals(CompareEntry other)
{
int weight = 0;
//Check whether the compared object is null.
if (Object.ReferenceEquals(other, null))
{
return false;
}
//Check whether the compared object references the same data.
if (Object.ReferenceEquals(this, other))
{
return true;
}
if ((this.CheckProperties(this.Email, other.Email) && this.Email == other.Email)
|| (this.CheckProperties(this.PhonePrivate, other.PhonePrivate) && this.PhonePrivate == other.PhonePrivate)
|| (this.CheckProperties(this.PhoneMobile, other.PhoneMobile) && this.PhoneMobile == other.PhoneMobile)
|| (this.CheckProperties(this.PhoneCompany, other.PhoneCompany) && this.PhoneCompany == other.PhoneCompany))
{
weight += 100;
}
if ((this.CheckProperties(this.Name, other.Name) && this.Name == other.Name)
|| (this.CheckProperties(this.FirstName, other.FirstName) && this.FirstName == other.FirstName))
{
weight += 25;
}
if ((this.CheckProperties(this.City, other.City) && this.City == other.City)
|| (this.CheckProperties(this.ZipCode, other.ZipCode) && this.ZipCode == other.ZipCode))
{
weight += 12;
}
if (this.CheckProperties(this.CompanyName, other.CompanyName) && this.CompanyName == other.CompanyName)
{
weight += 5;
}
return weight > 50;
}
public override int GetHashCode()
{
unchecked
{
int hash = (int)2166136261;
hash = hash * 16777619 ^ (string.IsNullOrEmpty(Email) ? 0 : Email.GetHashCode());
//hash = hash * 16777619 ^ (string.IsNullOrEmpty(PhonePrivate) ? 0 : PhonePrivate.GetHashCode());
//hash = hash * 16777619 ^ (string.IsNullOrEmpty(PhoneMobile) ? 0 : PhoneMobile.GetHashCode());
//hash = hash * 16777619 ^ (string.IsNullOrEmpty(PhoneCompany) ? 0 : PhoneCompany.GetHashCode());
//hash = hash * 16777619 ^ (string.IsNullOrEmpty(FirstName) ? 0 : FirstName.GetHashCode());
//hash = hash * 16777619 ^ (string.IsNullOrEmpty(Name) ? 0 : Name.GetHashCode());
//hash = hash * 16777619 ^ (string.IsNullOrEmpty(City) ? 0 : City.GetHashCode());
//hash = hash * 16777619 ^ (string.IsNullOrEmpty(ZipCode) ? 0 : ZipCode.GetHashCode());
//hash = hash * 16777619 ^ (string.IsNullOrEmpty(CompanyName) ? 0 : CompanyName.GetHashCode());
return hash;
}
}
private bool CheckProperties(string prop, string otherProp)
{
return !string.IsNullOrEmpty(prop) && !string.IsNullOrEmpty(otherProp);
}
}
问题是,当我重写GetHashCode()方法时,我只得到那些完全相同的人,或者在这种特殊情况下-只有相同的电子邮件。
我怎样才能有条件地检查GetHashCode()方法中的权重,以便我可以使用正确的方法Equals?或者是否有一种方法可以用其他方法进行相似性检查,哪种方法性能更好?
Equals
/GetHashCode
不是用来比较"基本相等"的事物的。等式在这里只是一个布尔属性。特别是,使用模糊的"基本相等"方法会导致及物性问题。Object.Equals
的文档包含如下要求:
如果
(x.Equals(y) && y.Equals(z))
返回true
,则x.Equals(z)
返回true
。
当你有模糊等式时,它就不成立了。仅仅因为x
"很像"y
和y
"很像"z
并不意味着x
"很像"z
。
现在你可以做的是有一个只比较电话号码的相等比较器,另一个只比较名字的相等比较器,等等-但这并不能真正得到模糊匹配