是否可以对 Dictionary 字符串键进行部分字符串匹配? [英] Is it possible to do a partial string match on a Dictionary string key?

问题描述

我的代码中有一个 Dictionary<string, List<int>>，我使用以下方式:

I have a Dictionary<string, List<int>> in my code which I am using in the following manner:

Key           Values  
2011-07-15    1, 2, 3
2011-07-20    4, 5, 6
2010-02-11    7, 8, 9

我的代码需要能够查询与键中特定子字符串匹配的所有值.例如，如果我有子字符串 2011-07，它应该返回值 {1, 2, 3, 4, 5, 6}.11 的子字符串应返回 1-9 中的所有 ID.

My code needs to be able to query for all values matching a particular substring in the key. For example, if I had the substring 2011-07 it should return values {1, 2, 3, 4, 5, 6}. A substring of 11 should return all IDs from 1-9.

谁能推荐一种简洁的方法来实现这一点?或者提供更好的数据结构来检索这些信息?

Can anyone recommend a concise way to achieve this? Or provide a better data structure for retrieving this information?

推荐答案

我会做一个扩展方法:

public static class DictionaryExt
{
    public static IEnumerable<T> PartialMatch<T>(this Dictionary<string, T> dictionary, string partialKey)
    {
        // This, or use a RegEx or whatever.
        IEnumerable<string> fullMatchingKeys = 
            dictionary.Keys.Where(currentKey => currentKey.Contains(partialKey));

        List<T> returnedValues = new List<T>();

        foreach (string currentKey in fullMatchingKeys)
        {
            returnedValues.Add(dictionary[currentKey]);
        }

        return returnedValues;
    }
}

向字典添加值的成本"不会改变，但检索成本会更高，但前提是您知道要进行部分匹配.

The "cost" of adding values to the dictionary wouldn't change, but the cost of retrieval would be higher, but only when you know you're going with a partial match.

顺便说一句，我相信您可以将其转换为单个 Lambda 表达式，但概念保持不变.

Btw, I'm sure you could transform this in a single Lambda expression, but the concept remains the same.

编辑:在您的示例中，此方法将返回 2 个值列表，但您可以更改它以合并列表.这是您可以做的扩展方法:

Edit: In your example, this method would return 2 lists of values, but you can change it to merge the lists. Here is the extension method you could do :

public static IEnumerable<T> PartialMatch<T>(
    this Dictionary<string, IEnumerable<T>> dictionary,
    string partialKey)
{
    // This, or use a RegEx or whatever.
    IEnumerable<string> fullMatchingKeys = 
        dictionary.Keys.Where(currentKey => currentKey.Contains(partialKey));

    List<T> returnedValues = new List<T>();

    foreach (string currentKey in fullMatchingKeys)
    {
        returnedValues.AddRange(dictionary[currentKey]);
    }

    return returnedValues;
}

编辑 2:想想看，你也可以让它更通用.使用下一个扩展方法，它适用于任何字典，只要您提供一个 comparer 来检查部分匹配"的含义:

Edit 2: Come to think of it, you could also make it more generic. With the next extension method, it would work on any dictionary, as long as you provide a comparer that check what you mean by "partial match" :

public static IEnumerable<TValue> PartialMatch<TKey, TValue>(
    this Dictionary<TKey, IEnumerable<TValue>> dictionary,
    TKey partialKey,
    Func<TKey, TKey, bool> comparer)
{
    // This, or use a RegEx or whatever.
    IEnumerable<TKey> fullMatchingKeys = 
        dictionary.Keys.Where(currentKey => comparer(partialKey, currentKey));

    List<TValue> returnedValues = new List<TValue>();

    foreach (TKey currentKey in fullMatchingKeys)
    {
        returnedValues.AddRange(dictionary[currentKey]);
    }

    return returnedValues;
}

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