在 C# 中的并发字典中交换键和值
Swap Key and Value in Concurrent Dictionary in C#
有什么方法可以在 C# 中的并发字典中交换键和值吗?我知道 Dictionary
类型,可以是
dictionary = dictionary.ToDictionary(x => x.Value, x => x.Key);
ConcurrentDictionary
中是否有类似内容?
您不能将 Dictionary 直接转换或转换为 ConcurrentDictionary。
Buy 你可以用字典创建一个 ConcurrentDictionary,检查这个构造函数
public ConcurrentDictionary(IEnumerable<KeyValuePair<TKey, TValue>> collection);
然后看看你说的LINQ的扩展方法
public static Dictionary<TKey, TElement> ToDictionary<TSource, TKey, TElement>(
this IEnumerable<TSource> source,
Func<TSource, TKey> keySelector,
Func<TSource, TElement> elementSelector);
所以如果 Dictionary
与 IEnumerable<KeyValuePair<TKey, TValue>>
兼容
解决方案 1
只需使用 LINQ 的 ToDictionary 扩展方法
var concurrentDict = new ConcurrentDictionary<string, string>();
/* Add some items */
bool firstItem = concurrentDict.TryAdd("1", "First"); //returns true
bool secondItem = concurrentDict.TryAdd("2", "Second"); //returns true
/* Swaping Value <-> Key to new Dictionary */
Dictionary<string,string> normalDict = concurrentDict.ToDictionary(x => x.Value, x => x.Key);
/* creating ConcurrentDictionary */
var newConcurrentDict = new ConcurrentDictionary<string, string>(normalDict);
解决方案 2
线程安全呢?
您可以使用自定义扩展方法(如 LINQ)
var concurrentDict = new ConcurrentDictionary<string, string>();
/* Add some items */
bool firstItem = concurrentDict.TryAdd("1", "First"); //returns true
bool secondItem = concurrentDict.TryAdd("2", "Second"); //returns true
/* Swaping Value <-> Key to new Dictionary */
Dictionary<string,string> normalDict = concurrentDict.ToDictionary(x => x.Value, x => x.Key);
/* creating ConcurrentDictionary */
var newConcurrentDict = normalDict.ToConcurrentDictionary();
扩展方法
参考
public static class ConcurrentDictionaryExtensions
{
public static ConcurrentDictionary<TKey, TElement> ToConcurrentDictionary<TSource, TKey, TElement>(
this IEnumerable<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector,
IEqualityComparer<TKey> comparer)
{
if (source == null) throw new ArgumentNullException("source");
if (keySelector == null) throw new ArgumentNullException("keySelector");
if (elementSelector == null) throw new ArgumentNullException("elementSelector");
ConcurrentDictionary<TKey, TElement> d = new ConcurrentDictionary<TKey, TElement>(comparer);
foreach (TSource element in source)
d.TryAdd(keySelector(element), elementSelector(element));
return d;
}
public static ConcurrentDictionary<TKey, TSource> ToConcurrentDictionary<TSource, TKey>(
this IEnumerable<TSource> source, Func<TSource, TKey> keySelector)
{
return ToConcurrentDictionary<TSource, TKey, TSource>(source, keySelector, IdentityFunction<TSource>.Instance,
null);
}
public static ConcurrentDictionary<TKey, TSource> ToConcurrentDictionary<TSource, TKey>(
this IEnumerable<TSource> source, Func<TSource, TKey> keySelector, IEqualityComparer<TKey> comparer)
{
return ToConcurrentDictionary<TSource, TKey, TSource>(source, keySelector, IdentityFunction<TSource>.Instance,
comparer);
}
public static ConcurrentDictionary<TKey, TElement> ToConcurrentDictionary<TSource, TKey, TElement>(
this IEnumerable<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector)
{
return ToConcurrentDictionary<TSource, TKey, TElement>(source, keySelector, elementSelector, null);
}
internal class IdentityFunction<TElement>
{
public static Func<TElement, TElement> Instance
{
get { return x => x; }
}
}
}
有什么方法可以在 C# 中的并发字典中交换键和值吗?我知道 Dictionary
类型,可以是
dictionary = dictionary.ToDictionary(x => x.Value, x => x.Key);
ConcurrentDictionary
中是否有类似内容?
您不能将 Dictionary 直接转换或转换为 ConcurrentDictionary。 Buy 你可以用字典创建一个 ConcurrentDictionary,检查这个构造函数
public ConcurrentDictionary(IEnumerable<KeyValuePair<TKey, TValue>> collection);
然后看看你说的LINQ的扩展方法
public static Dictionary<TKey, TElement> ToDictionary<TSource, TKey, TElement>(
this IEnumerable<TSource> source,
Func<TSource, TKey> keySelector,
Func<TSource, TElement> elementSelector);
所以如果 Dictionary
与 IEnumerable<KeyValuePair<TKey, TValue>>
解决方案 1
只需使用 LINQ 的 ToDictionary 扩展方法
var concurrentDict = new ConcurrentDictionary<string, string>();
/* Add some items */
bool firstItem = concurrentDict.TryAdd("1", "First"); //returns true
bool secondItem = concurrentDict.TryAdd("2", "Second"); //returns true
/* Swaping Value <-> Key to new Dictionary */
Dictionary<string,string> normalDict = concurrentDict.ToDictionary(x => x.Value, x => x.Key);
/* creating ConcurrentDictionary */
var newConcurrentDict = new ConcurrentDictionary<string, string>(normalDict);
解决方案 2
线程安全呢?
您可以使用自定义扩展方法(如 LINQ)
var concurrentDict = new ConcurrentDictionary<string, string>();
/* Add some items */
bool firstItem = concurrentDict.TryAdd("1", "First"); //returns true
bool secondItem = concurrentDict.TryAdd("2", "Second"); //returns true
/* Swaping Value <-> Key to new Dictionary */
Dictionary<string,string> normalDict = concurrentDict.ToDictionary(x => x.Value, x => x.Key);
/* creating ConcurrentDictionary */
var newConcurrentDict = normalDict.ToConcurrentDictionary();
扩展方法
参考
public static class ConcurrentDictionaryExtensions
{
public static ConcurrentDictionary<TKey, TElement> ToConcurrentDictionary<TSource, TKey, TElement>(
this IEnumerable<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector,
IEqualityComparer<TKey> comparer)
{
if (source == null) throw new ArgumentNullException("source");
if (keySelector == null) throw new ArgumentNullException("keySelector");
if (elementSelector == null) throw new ArgumentNullException("elementSelector");
ConcurrentDictionary<TKey, TElement> d = new ConcurrentDictionary<TKey, TElement>(comparer);
foreach (TSource element in source)
d.TryAdd(keySelector(element), elementSelector(element));
return d;
}
public static ConcurrentDictionary<TKey, TSource> ToConcurrentDictionary<TSource, TKey>(
this IEnumerable<TSource> source, Func<TSource, TKey> keySelector)
{
return ToConcurrentDictionary<TSource, TKey, TSource>(source, keySelector, IdentityFunction<TSource>.Instance,
null);
}
public static ConcurrentDictionary<TKey, TSource> ToConcurrentDictionary<TSource, TKey>(
this IEnumerable<TSource> source, Func<TSource, TKey> keySelector, IEqualityComparer<TKey> comparer)
{
return ToConcurrentDictionary<TSource, TKey, TSource>(source, keySelector, IdentityFunction<TSource>.Instance,
comparer);
}
public static ConcurrentDictionary<TKey, TElement> ToConcurrentDictionary<TSource, TKey, TElement>(
this IEnumerable<TSource> source, Func<TSource, TKey> keySelector, Func<TSource, TElement> elementSelector)
{
return ToConcurrentDictionary<TSource, TKey, TElement>(source, keySelector, elementSelector, null);
}
internal class IdentityFunction<TElement>
{
public static Func<TElement, TElement> Instance
{
get { return x => x; }
}
}
}