What is the best way to clone deep copy a NET generic Dictionary string T

Question

I ve got a generic dictionary Dictionary lt string  T gt  that I would like to essentially make a Clone   of   any suggestions

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This works fine for me      assuming this fills the List  List lt Dictionary lt string  string gt  gt  obj   this getData       List lt Dictionary lt string  string gt  gt  objCopy   new List lt Dictionary lt string  string gt  gt  obj     As Tomer Wolberg describes in the comments  this does not work if the value type is a mutable class

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Try this if key values are ICloneable       public static Dictionary lt K V gt  CloneDictionary lt K V gt  Dictionary lt K V gt  dict  where K   ICloneable where V   ICloneable               Dictionary lt K  V gt  newDict   null           if  dict    null                           If the key and value are value types  just use copy constructor              if    typeof K  IsValueType    typeof K     typeof string    amp  amp                    typeof V  IsValueType     typeof V     typeof string                                  newDict   new Dictionary lt K  V gt  dict                             else    prepare to clone key or value or both                               newDict   new Dictionary lt K  V gt                      foreach  KeyValuePair lt K  V gt  kvp in dict                                        K key                      if  typeof K  IsValueType    typeof K     typeof string                                                 key   kvp Key                                            else                                               key    K kvp Key Clone                                              V value                      if  typeof V  IsValueType    typeof V     typeof string                                                 value   kvp Value                                            else                                               value    V kvp Value Clone                                               newDict key    value                                                     return newDict

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Binary Serialization method works fine but in my tests it showed to be 10x slower than a non-serialization implementation of clone  Tested it on Dictionary lt string   List lt double gt  gt

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That s what helped me  when I was trying to deep copy a Dictionary  lt  string  string     Dictionary lt string  string gt  dict2   new Dictionary lt string  string gt  dict     Good luck

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Replying on old post however I found it useful to wrap it as follows   using System  using System Collections Generic   public class DeepCopy     public static Dictionary lt T1  T2 gt  CloneKeys lt T1  T2 gt  Dictionary lt T1  T2 gt  dict      where T1   ICloneable         if  dict    null        return null      Dictionary lt T1  T2 gt  ret   new Dictionary lt T1  T2 gt         foreach  var e in dict        ret  T1 e Key Clone      e Value      return ret         public static Dictionary lt T1  T2 gt  CloneValues lt T1  T2 gt  Dictionary lt T1  T2 gt  dict      where T2   ICloneable         if  dict    null        return null      Dictionary lt T1  T2 gt  ret   new Dictionary lt T1  T2 gt         foreach  var e in dict        ret e Key     T2  e Value Clone         return ret         public static Dictionary lt T1  T2 gt  Clone lt T1  T2 gt  Dictionary lt T1  T2 gt  dict      where T1   ICloneable     where T2   ICloneable         if  dict    null        return null      Dictionary lt T1  T2 gt  ret   new Dictionary lt T1  T2 gt         foreach  var e in dict        ret  T1 e Key Clone       T2  e Value Clone         return ret

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Okay  the  NET 2 0 answers   If you don t need to clone the values  you can use the constructor overload to Dictionary which takes an existing IDictionary   You can specify the comparer as the existing dictionary s comparer  too    If you do need to clone the values  you can use something like this   public static Dictionary lt TKey  TValue gt  CloneDictionaryCloningValues lt TKey  TValue gt      Dictionary lt TKey  TValue gt  original  where TValue   ICloneable       Dictionary lt TKey  TValue gt  ret   new Dictionary lt TKey  TValue gt  original Count                                                              original Comparer       foreach  KeyValuePair lt TKey  TValue gt  entry in original                ret Add entry Key   TValue  entry Value Clone               return ret      That relies on TValue Clone   being a suitably deep clone as well  of course

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For  NET 2 0 you could implement a class which inherits from Dictionary and implements ICloneable   public class CloneableDictionary lt TKey  TValue gt    Dictionary lt TKey  TValue gt  where TValue   ICloneable       public IDictionary lt TKey  TValue gt  Clone                 CloneableDictionary lt TKey  TValue gt  clone   new CloneableDictionary lt TKey  TValue gt              foreach  KeyValuePair lt TKey  TValue gt  pair in this                        clone Add pair Key   TValue pair Value Clone                        return clone            You can then clone the dictionary simply by calling the Clone method  Of course this implementation requires that the value type of the dictionary implements ICloneable  but otherwise a generic implementation isn t practical at all

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Dictionary lt string  int gt  dictionary   new Dictionary lt string  int gt      Dictionary lt string  int gt  copy   new Dictionary lt string  int gt  dictionary

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Note  although the cloning version is potentially useful  for a simple shallow copy the constructor I mention in the other post is a better option    How deep do you want the copy to be  and what version of  NET are you using  I suspect that a LINQ call to ToDictionary  specifying both the key and element selector  will be the easiest way to go if you re using  NET 3 5   For instance  if you don t mind the value being a shallow clone   var newDictionary   oldDictionary ToDictionary entry   gt  entry Key                                                 entry   gt  entry Value     If you ve already constrained T to implement ICloneable   var newDictionary   oldDictionary ToDictionary entry   gt  entry Key                                                  entry   gt   T  entry Value Clone        Those are untested  but should work

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The best way for me is this   Dictionary lt int  int gt  copy  new Dictionary lt int  int gt  yourListOrDictionary

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In the case you have a Dictionary of  quot object quot  and object can be anything like  double  int      or ComplexClass   Dictionary lt string  object gt  dictSrc   get  set     public class ComplexClass   ICloneable            private Point3D          private Vector3D                      public object Clone                 ComplexClass clone   new ComplexClass            clone    ComplexClass this MemberwiseClone            return clone             dictSrc  quot toto quot     new ComplexClass   dictSrc  quot tata quot     12 3      dictDest   dictSrc ToDictionary entry   gt  entry Key                                  entry   gt    entry Value is ICloneable     entry Value as ICloneable  Clone     entry Value

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You could always use serialization  You could serialize the object then deserialize it  That will give you a deep copy of the Dictionary and all the items inside of it  Now you can create a deep copy of any object that is marked as  Serializable  without writing any special code   Here are two methods that will use Binary Serialization  If you use these methods you simply call   object deepcopy   FromBinary ToBinary yourDictionary     public Byte   ToBinary       MemoryStream ms   null    Byte   byteArray   null    try         BinaryFormatter serializer   new BinaryFormatter        ms   new MemoryStream        serializer Serialize ms  this       byteArray   ms ToArray          catch  Exception unexpected          Trace Fail unexpected Message       throw        finally         if  ms    null        ms Close          return byteArray     public object FromBinary Byte   buffer      MemoryStream ms   null    object deserializedObject   null     try         BinaryFormatter serializer   new BinaryFormatter        ms   new MemoryStream        ms Write buffer  0  buffer Length       ms Position   0      deserializedObject   serializer Deserialize ms         finally         if  ms    null        ms Close          return deserializedObject

[c#] What is the best way to clone/deep copy a .NET generic Dictionary<string, T>?

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