比较两本词典是否相等-C#/.NET问题

Compare two dictionaries for equality(比较两本词典是否相等)

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));
        }
    }
}

比较这类词典的正确方式是什么？还是我的TestSuite(诚然写得很拙劣)中有错误？

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。

AreDictionariesEqualit 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编程学习网！