我有以下数组,它代表我试图从某个数据结构实例中删除的项目:
string[] diseasesToRemove = new string[] { "D1", "D3", "D5" };
我可以使用以下方法做到这一点:
for (int i = 0; i < healthGroup.DiseaseGroups.Length; i++)
{
var dgDiseases = new List<Disease>(healthGroup.DiseaseGroups[i].Diseases);
for (int j = 0; j < dgDiseases.Count; j++)
{
if (diseasesToRemove.Contains(dgDiseases[j].Name))
{
dgDiseases.RemoveAt(j);
j--;
}
}
healthGroup.DiseaseGroups[i].Diseases = dgDiseases.ToArray();
}
不过,我确信有更好的方法使用 Linq 或其他工具。有吗?
这里是类:
public class HealthGroup
{
public DiseaseGroup[] DiseaseGroups { get; set; }
public HealthGroup(DiseaseGroup[] diseaseGroups)
{
DiseaseGroups = diseaseGroups;
}
}
public class DiseaseGroup
{
public string Name { get; set; }
public Disease[] Diseases;
public DiseaseGroup(string name, Disease[] diseases)
{
Name = name;
Diseases = diseases;
}
}
public class Disease
{
public string Name { get; set; } = "My Disease";
public int Risk { get; set; } = 7;
public Disease(string name, int risk)
{
Name = name;
Risk = risk;
}
public override string ToString()
{
return $"{Name} with risk {Risk}";
}
}
还有一些生成实例的样板:
Disease d1 = new Disease("D1", 1);
Disease d2 = new Disease("D2", 2);
Disease d3 = new Disease("D3", 3);
Disease d4 = new Disease("D4", 4);
Disease d5 = new Disease("D5", 5);
Disease d6 = new Disease("D6", 6);
Disease d7 = new Disease("D7", 7);
DiseaseGroup dg1 = new DiseaseGroup("DG1", new Disease[] { d1, d2 });
DiseaseGroup dg2 = new DiseaseGroup("DG2", new Disease[] { d3, d4, d5 });
DiseaseGroup dg3 = new DiseaseGroup("DG3", new Disease[] { d6, d7 });
HealthGroup healthGroup = new HealthGroup(new DiseaseGroup[] { dg1, dg2, dg3 });
最佳答案
你可以使用 Where
将代码简化为:
foreach (var diseaseGroup in healthGroup.DiseaseGroups)
{
diseaseGroup.Diseases
= diseaseGroup.Diseases.Where(g => !diseasesToRemove.Contains(g.Name)).ToArray();
}
当然,与原始代码一样,这会生成一个新列表。一个性能更高的选项(尽管是非 LINQ)可能是制作 Diseases
一个List<Disease>
:
public class DiseaseGroup
{
public string Name { get; set; }
public List<Disease> Diseases;
public DiseaseGroup(string name, Disease[] diseases)
{
Name = name;
Diseases = new List<Disease>(diseases);
}
}
然后您可以使用类似的代码,而无需生成新列表和新数组的开销:
for (int i = 0; i < healthGroup.DiseaseGroups.Length; i++)
{
for (int j = healthGroup.DiseaseGroups[i].Diseases.Count - 1; j >= 0; --j)
{
if (diseasesToRemove.Contains(healthGroup.DiseaseGroups[i].Diseases[j].Name))
{
healthGroup.DiseaseGroups[i].Diseases.RemoveAt(j);
}
}
}
我还修改了您的 for 循环以向后工作以解决您在 --j
中遇到的问题部分。
并且,而不是使用 string[]
对于 diseasesToRemove
,对于大量项目,使用 HashSet<string>
可能会更好储存疾病。
编辑以包括请求的一行:
healthGroup.DiseaseGroups = healthGroup.DiseaseGroups.Select(g => { return g.Diseases = g.Diseases.Where(g => !diseasesToRemove.Contains(g.Name)).ToArray(); }).ToArray();
不过,这有点滥用选择 :-)
关于c# - 如何使用linq删除项目,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/52106916/