C# List<T>取并集并去重的两种方法时间消耗比较

文章目录

C# List\取并集并去重的两种方法时间消耗比较
前言
一、两种方法
二、时间计算方法
- 1.Stopwatch
三、数据
四、总代码
结果总结

前言

当时是个人要对泛型集合进行合并并且去除重复项，这里有个要点：
– 对于值类型：可以直接操作。
– 对于引用类型：要继承IEqualityComparer()接口实现新的比较方法，来适应你的类型。

结尾有全部代码

一、两种方法

第一种：不调用其他方法，直接对集合AddRange再Distinct去重

example.AddRange(example);
example.ToList().Distinct();

第二种：调用Linq的Union方法

example.Union(lastSameExample).ToList();

二、时间计算方法

1.Stopwatch

//时间监视方法
Dictionary<string, double> timeDictionary1 = new Dictionary<string, double>();Stopwatch stopwatch = new Stopwatch();stopwatch.Start();
example.AddRange(example);
example.ToList().Distinct();
stopwatch.Stop();
//获取时间(ms)
timeDictionary1.Add("SameList",stopwatch.Elapsed.TotalMilliseconds);

三、数据

取26个字母放入字符串列表：
完全不相同、第一个相同、最后一个相同、中间的相同

 List<string> example = new List<string>()
{"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"
};
List<string> notSameExample = new List<string>()
{"a","bb","cc","dd","ee","ff","gg","hh","ii","jj","kk","ll","mm","nn","oo","pp","qq","rr","ss","tt","uu","vv","ww","xx","yy","zz"
};List<string> firstSameExample = new List<string>()
{"a","bb","cc","dd","ee","ff","gg","hh","ii","jj","kk","ll","mm","nn","oo","pp","qq","rr","ss","tt","uu","vv","ww","xx","yy","zz"
};
List<string> lastSameExample = new List<string>()
{"aa","bb","cc","dd","ee","ff","gg","hh","ii","jj","kk","ll","mm","nn","oo","pp","qq","rr","ss","tt","uu","vv","ww","xx","yy","z"
};
List<string> middleSameExample = new List<string>()
{"aa","bb","cc","dd","ee","ff","gg","hh","ii","jj","kk","ll","m","nn","oo","pp","qq","rr","ss","tt","uu","vv","ww","xx","yy","z"
};

四、总代码

public void Method_TimeUse(){List<string> example = new List<string>(){"a","b","c","d","e","f","g","h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"};List<string> notSameExample = new List<string>(){"a","bb","cc","dd","ee","ff","gg","hh","ii","jj","kk","ll","mm","nn","oo","pp","qq","rr","ss","tt","uu","vv","ww","xx","yy","zz"};List<string> firstSameExample = new List<string>(){"a","bb","cc","dd","ee","ff","gg","hh","ii","jj","kk","ll","mm","nn","oo","pp","qq","rr","ss","tt","uu","vv","ww","xx","yy","zz"};List<string> lastSameExample = new List<string>(){"aa","bb","cc","dd","ee","ff","gg","hh","ii","jj","kk","ll","mm","nn","oo","pp","qq","rr","ss","tt","uu","vv","ww","xx","yy","z"};List<string> middleSameExample = new List<string>(){"aa","bb","cc","dd","ee","ff","gg","hh","ii","jj","kk","ll","m","nn","oo","pp","qq","rr","ss","tt","uu","vv","ww","xx","yy","z"};Dictionary<string, double> timeDictionary1 = new Dictionary<string, double>();Dictionary<string, double> timeDictionary2 = new Dictionary<string, double>();//时间监视方法Stopwatch stopwatch = new Stopwatch();//第一种：不调用其他方法，直接对集合AddRange再Distinct去重stopwatch.Start();example.AddRange(example);example.ToList().Distinct();stopwatch.Stop();timeDictionary1.Add("SameList",stopwatch.Elapsed.TotalMilliseconds);stopwatch.Start();example.AddRange(notSameExample);example.ToList().Distinct();stopwatch.Stop();timeDictionary1.Add("NotSameList", stopwatch.Elapsed.TotalMilliseconds);stopwatch.Start();example.AddRange(firstSameExample);example.ToList().Distinct();stopwatch.Stop();timeDictionary1.Add("FirstSameList", stopwatch.Elapsed.TotalMilliseconds);stopwatch.Start();example.AddRange(lastSameExample);example.ToList().Distinct();stopwatch.Stop();timeDictionary1.Add("LastSameList", stopwatch.Elapsed.TotalMilliseconds);stopwatch.Start();example.AddRange(middleSameExample);example.ToList().Distinct();stopwatch.Stop();timeDictionary1.Add("MiddleSameList", stopwatch.Elapsed.TotalMilliseconds);//第二种：调用Union方法stopwatch.Start();example.Union(example).ToList();stopwatch.Stop();timeDictionary2.Add("SameList", stopwatch.Elapsed.TotalMilliseconds);stopwatch.Start();example.Union(notSameExample).ToList();stopwatch.Stop();timeDictionary2.Add("NotSameList", stopwatch.Elapsed.TotalMilliseconds);stopwatch.Start();example.Union(firstSameExample).ToList();stopwatch.Stop();timeDictionary2.Add("FirstSameList", stopwatch.Elapsed.TotalMilliseconds);stopwatch.Start();example.Union(lastSameExample).ToList();stopwatch.Stop();timeDictionary2.Add("LastSameList", stopwatch.Elapsed.TotalMilliseconds);stopwatch.Start();example.Union(middleSameExample).ToList();stopwatch.Stop();timeDictionary2.Add("MiddleSameList", stopwatch.Elapsed.TotalMilliseconds);_testOutputHelper.WriteLine("第一种：不调用其他方法，直接对集合AddRange再Distinct去重");foreach(var item in timeDictionary1){_testOutputHelper.WriteLine($"ListType:{item.Key}   TimeUse:{item.Value}");}_testOutputHelper.WriteLine("第二种：调用Union方法");foreach (var item in timeDictionary2){_testOutputHelper.WriteLine($"ListType:{item.Key}   TimeUse:{item.Value}");}}

结果总结

Union方法中有着其他的过程，但具体个人并未深入。
就图中结果而言，差距很大，还是老老实实用第一个吧。
本人新手，欢迎各位大佬指点一二。

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【知识学习】C# List＜T＞取并集并去重的两种方法时间消耗比较

C# List<T>取并集并去重的两种方法时间消耗比较

文章目录

前言

一、两种方法

二、时间计算方法

1.Stopwatch

三、数据

四、总代码

结果总结

【知识学习】C# List＜T＞取并集并去重的两种方法时间消耗比较相关推荐

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