Question

我有对象列表：

public class SDesc
{
    public string sensorId { get; set; }
    public string address { get; set; }
}

List<SDesc> desc = new List<SDesc>
{
    new SDesc {sensorId = "1234", address =   "Adams22"},
    new SDesc {sensorId = "5555", address =   "Hourton34"},
    new SDesc {sensorId = "4444", address =   "SaintsRoad55"},
    new SDesc {sensorId = "1258", address =   "BerryAve58"},
    new SDesc {sensorId = "52486", address =   "SaintsRoad2"},
    new SDesc {sensorId = "12361", address =   "TomassonRoad"}
}

我也有IEnumarable字符串：

IEnumarable<string> sId = {"4444","52486","12361"};

来自 desc 列表我需要删除sId列表中sensorId属性存在的记录。

例如，对于上述情况，我想得到的结果是：

List<SDesc> desc = new List<SDesc>
{
    new SDesc {sensorId = "1234", address =   "Adams22"},
    new SDesc {sensorId = "5555", address =   "Hourton34"},
    new SDesc {sensorId = "1258", address =   "BerryAve58"},
}

这是我试过的：

desc.RemoveAll(obj => obj.sensorId == sId);

但它不能正常工作，因为sID是IEnumarable类型。

所以我的问题是如何从 desc 列表中移除物品，其中sensorsId属性存在于sId列表中？

Answer 1

您需要使用Any，例如：

 desc.RemoveAll(obj => sId.Any(x=> x== obj.sensorId ));

正如方法名称建议的那样，它会检查sId中的任何项目是否与desc中sensorId的项目相匹配，它会从List<T>中移除这些项目。

Answer 2

您可以使用.Contains() LINQ方法检查集合是否包含项目：

desc.RemoveAll(obj => sId.Contains(obj.sensorId));

但是，它会导致枚举sId的多次枚举。在这种情况下，这不是问题，因为这个可枚举的数组是，在这种特殊情况下。

详细了解“可能的多重枚举”：
- Handling warning for possible multiple enumeration of IEnumerable
- Resharper's example code for explaining "Possible multiple enumeration of IEnumerable"

我建议将其转换为一个集合，以确保只列举一次IEnumerable 正如Evk在评论中所建议的那样，最好使用HashSet以便.Contains在O(1)时间内执行：

List<SDesc> desc = new List<SDesc> {
  new SDesc {sensorId = "1234", address =   "Adams22"},
  new SDesc {sensorId = "5555", address =   "Hourton34"},
  new SDesc {sensorId = "4444", address =   "SaintsRoad55"},
  new SDesc {sensorId = "1258", address =   "BerryAve58"},
  new SDesc {sensorId = "52486", address =   "SaintsRoad2"},
  new SDesc {sensorId = "12361", address =   "TomassonRoad"}
};

IEnumarable<string> sId = {"4444","52486","12361"};
var sIdsSet = new HashSet(sId);

desc.RemoveAll(obj => sIdsSet.Contains(obj.sensorId));

从对象列表中删除特定项目

2 个答案: