比较两本词典是否相等 [英] Compare two dictionaries for equality
本文介绍了比较两本词典是否相等的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！
问题描述
我想在C#中比较两个作为键astring和作为值的ints的字典。我假设两个字典都具有相同的键，并且对于每个键作为值都有一个具有相同整数的列表(两者不必以相同的顺序)。
我使用了this和this相关问题中的两个答案，但都没有通过测试函数DoesOrderKeysMatter和DoesOrderValuesMatter的测试套件。
我的测试套件：
using System;
using Microsoft.VisualStudio.TestTools.UnitTesting;
using System.Collections.Generic;
using System.Linq;
namespace UnitTestProject1
{
[TestClass]
public class ProvideReportTests
{
[TestMethod]
public void AreSameDictionariesEqual()
{
// arrange
Dictionary<string, List<int>> dict1 = new Dictionary<string, List<int>>();
List<int> list1 = new List<int>();
list1.Add(1);
list1.Add(2);
dict1.Add("a", list1);
List<int> list2 = new List<int>();
list2.Add(3);
list2.Add(4);
dict1.Add("b", list2);
// act
bool dictsAreEqual = false;
dictsAreEqual = AreDictionariesEqual(dict1, dict1);
// assert
Assert.IsTrue(dictsAreEqual, "Dictionaries are not equal");
}
[TestMethod]
public void AreDifferentDictionariesNotEqual()
{
// arrange
Dictionary<string, List<int>> dict1 = new Dictionary<string, List<int>>();
List<int> list1 = new List<int>();
list1.Add(1);
list1.Add(2);
dict1.Add("a", list1);
List<int> list2 = new List<int>();
list2.Add(3);
list2.Add(4);
dict1.Add("b", list2);
Dictionary<string, List<int>> dict2 = new Dictionary<string, List<int>>();
// act
bool dictsAreEqual = true;
dictsAreEqual = AreDictionariesEqual(dict1, dict2);
// assert
Assert.IsFalse(dictsAreEqual, "Dictionaries are equal");
}
[TestMethod]
public void DoesOrderKeysMatter()
{
// arrange
Dictionary<string, List<int>> dict1 = new Dictionary<string, List<int>>();
List<int> list1 = new List<int>();
list1.Add(1);
list1.Add(2);
dict1.Add("a", list1);
List<int> list2 = new List<int>();
list2.Add(3);
list2.Add(4);
dict1.Add("b", list2);
Dictionary<string, List<int>> dict2 = new Dictionary<string, List<int>>();
List<int> list3 = new List<int>();
list3.Add(3);
list3.Add(4);
dict2.Add("b", list3);
List<int> list4 = new List<int>();
list4.Add(1);
list4.Add(2);
dict2.Add("a", list4);
// act
bool dictsAreEqual = false;
dictsAreEqual = AreDictionariesEqual(dict1, dict2);
// assert
Assert.IsTrue(dictsAreEqual, "Dictionaries are not equal");
}
[TestMethod]
public void DoesOrderValuesMatter()
{
// arrange
Dictionary<string, List<int>> dict1 = new Dictionary<string, List<int>>();
List<int> list1 = new List<int>();
list1.Add(1);
list1.Add(2);
dict1.Add("a", list1);
List<int> list2 = new List<int>();
list2.Add(3);
list2.Add(4);
dict1.Add("b", list2);
Dictionary<string, List<int>> dict2 = new Dictionary<string, List<int>>();
List<int> list3 = new List<int>();
list3.Add(2);
list3.Add(1);
dict2.Add("a", list3);
List<int> list4 = new List<int>();
list4.Add(4);
list4.Add(3);
dict2.Add("b", list4);
// act
bool dictsAreEqual = false;
dictsAreEqual = AreDictionariesEqual(dict1, dict2);
// assert
Assert.IsTrue(dictsAreEqual, "Dictionaries are not equal");
}
private bool AreDictionariesEqual(Dictionary<string, List<int>> dict1, Dictionary<string, List<int>> dict2)
{
return dict1.Keys.Count == dict2.Keys.Count &&
dict1.Keys.All(k => dict2.ContainsKey(k) && object.Equals(dict2[k], dict1[k]));
// also fails:
// return dict1.OrderBy(kvp => kvp.Key).SequenceEqual(dict2.OrderBy(kvp => kvp.Key));
}
}
}
更新
我正在尝试将Servy的答案合并到我的测试套件中，如下所示，但我收到一些错误(在Visual Studio中用红色的摆动线条下划线)：
SetEquals在`Equals方法中表示：&Quot；不包含接受Generic.List类型的第一个参数的SetEquals的定义。AreDictionariesEqual
it saysDictionaryComparer<；List>；中的是类型，但用作变量。`
namespace UnitTestProject1 { [TestClass] public class ProvideReportTests { [TestMethod] // ... same as above private bool AreDictionariesEqual(Dictionary<string, List<int>> dict1, Dictionary<string, List<int>> dict2) { DictionaryComparer<string, List<int>>(new ListComparer<int>() dc = new DictionaryComparer<string, List<int>>(new ListComparer<int>(); return dc.Equals(dict1, dict2); } } public class DictionaryComparer<TKey, TValue> : IEqualityComparer<Dictionary<TKey, TValue>> { private IEqualityComparer<TValue> valueComparer; public DictionaryComparer(IEqualityComparer<TValue> valueComparer = null) { this.valueComparer = valueComparer ?? EqualityComparer<TValue>.Default; } public bool Equals(Dictionary<TKey, TValue> x, Dictionary<TKey, TValue> y) { if (x.Count != y.Count) return false; if (x.Keys.Except(y.Keys).Any()) return false; if (y.Keys.Except(x.Keys).Any()) return false; foreach (var pair in x) if (!valueComparer.Equals(pair.Value, y[pair.Key])) return false; return true; } public int GetHashCode(Dictionary<TKey, TValue> obj) { throw new NotImplementedException(); } } public class ListComparer<T> : IEqualityComparer<List<T>> { private IEqualityComparer<T> valueComparer; public ListComparer(IEqualityComparer<T> valueComparer = null) { this.valueComparer = valueComparer ?? EqualityComparer<T>.Default; } public bool Equals(List<T> x, List<T> y) { return x.SetEquals(y, valueComparer); } public int GetHashCode(List<T> obj) { throw new NotImplementedException(); } } public static bool SetEquals<T>(this IEnumerable<T> first, IEnumerable<T> second, IEqualityComparer<T> comparer) { return new HashSet<T>(second, comparer ?? EqualityComparer<T>.Default) .SetEquals(first); } }
推荐答案
所以首先我们需要一个字典的相等比较器。它需要确保它们具有匹配的键，如果匹配，则比较每个键的值：
public class DictionaryComparer<TKey, TValue> :
IEqualityComparer<Dictionary<TKey, TValue>>
{
private IEqualityComparer<TValue> valueComparer;
public DictionaryComparer(IEqualityComparer<TValue> valueComparer = null)
{
this.valueComparer = valueComparer ?? EqualityComparer<TValue>.Default;
}
public bool Equals(Dictionary<TKey, TValue> x, Dictionary<TKey, TValue> y)
{
if (x.Count != y.Count)
return false;
if (x.Keys.Except(y.Keys).Any())
return false;
if (y.Keys.Except(x.Keys).Any())
return false;
foreach (var pair in x)
if (!valueComparer.Equals(pair.Value, y[pair.Key]))
return false;
return true;
}
public int GetHashCode(Dictionary<TKey, TValue> obj)
{
throw new NotImplementedException();
}
}
但这本身是不够的。我们需要使用另一个自定义比较器(而不是默认比较器)比较字典的值，因为默认列表比较器不会查看列表的值：
public class ListComparer<T> : IEqualityComparer<List<T>>
{
private IEqualityComparer<T> valueComparer;
public ListComparer(IEqualityComparer<T> valueComparer = null)
{
this.valueComparer = valueComparer ?? EqualityComparer<T>.Default;
}
public bool Equals(List<T> x, List<T> y)
{
return x.SetEquals(y, valueComparer);
}
public int GetHashCode(List<T> obj)
{
throw new NotImplementedException();
}
}
它使用以下扩展方法：
public static bool SetEquals<T>(this IEnumerable<T> first, IEnumerable<T> second,
IEqualityComparer<T> comparer)
{
return new HashSet<T>(second, comparer ?? EqualityComparer<T>.Default)
.SetEquals(first);
}
现在我们可以简单地写成：
new DictionaryComparer<string, List<int>>(new ListComparer<int>())
.Equals(dict1, dict2);
这篇关于比较两本词典是否相等的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！
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