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比较字典中的等式

compare dictionary c#

-3

BaltoStar · 技术社区 · 7 年前

如何最有效地比较两本字典以实现平等?--除了键的强制迭代外,尝试查找和比较值

var d1 = new Dictionary<string,int>();
d1.Add("a",2);
d1.Add("b",1);
d1.Add("c",1);

var d2 = new Dictionary<string,int>();
d2.Add("c",1);
d2.Add("b",1);
d2.Add("a",2);

如何最有效地比较平等?

不是这样的暴力:

static bool CompareDictionaries(Dictionary<string,int> d1, Dictionary<string,int> d2)
{
    if (d1.Count != d2.Count) return false;
    foreach(string key in d1.Keys)
    {
        if (!d2.ContainsKey(key)) return false;
        if (d1[key] != d2[key]) return false;
    }
    return true;
}

2 回复 | 直到 7 年前

-1

Gauravsa 7 年前

如果字典键相同,可以使用HashSet进行比较:

var set1 = new HashSet<int>(dictionary1.Values);
var set2 = new HashSet<int>(dictionary2.Values);

然后可以使用Union、Intersect,除非由HashSet公开。此外,您还可以使用:

bool isEqual = set1.SetEquals(set2);

根据您的情况,基准测试是(HashSet vs Dictionary) here

-1

Parrish Husband 7 年前

加上习俗 SequenceEquals 扩展名,您可以指定如何比较键和值,如下所示:

public static bool Equals<TKey, TValue>(IDictionary<TKey, TValue> a, IDictionary<TKey, TValue> b,
    IComparer<TKey> keyComparer, IEqualityComparer<TValue> valueComparer)
{
    if (ReferenceEquals(a, b))
        return true;

    if (b == null || a == null)
        return false;

    if (a.Count != b.Count)
        return false;

    var aOrdered = a.OrderBy(k => k.Key, keyComparer);
    var bOrdered = b.OrderBy(k => k.Key, keyComparer);

    return aOrdered.SequenceEqual(bOrdered, valueComparer);
}

分机:

public static bool SequenceEqual<TKey, TValue>(this IEnumerable<KeyValuePair<TKey, TValue>> first, IEnumerable<KeyValuePair<TKey, TValue>> second, IEqualityComparer<TValue> valueComparer)
{
    if (valueComparer == null) valueComparer = EqualityComparer<TValue>.Default;
    if (first == null) throw new ArgumentNullException(nameof(first));
    if (second == null) throw new ArgumentNullException(nameof(second));

    using (IEnumerator<KeyValuePair<TKey, TValue>> e1 = first.GetEnumerator())
    using (IEnumerator<KeyValuePair<TKey, TValue>> e2 = second.GetEnumerator())
    {
        while (e1.MoveNext())
        {
            if (!(e2.MoveNext() && valueComparer.Equals(e1.Current.Value, e2.Current.Value))) return false;
        }
        if (e2.MoveNext()) return false;
    }
    return true;
}

Dictionary<string,int> 例子:

var areEqual = Equals(d1, d2, StringComparer.OrdinalIgnoreCase, EqualityComparer<int>.Default);