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c#dictionarymerge
Ks_Hamza
Ks_Hamza

Reputation: 81

merge two dictionaries Dictionary<string, Dictionary<string, Object>>

This is kind-of related to this question, on how to merge two dictionaries in C#. An elegant Linq solution is presented, which is cool.

However, that question relates to Dictionary<Object1, Object2>, whereas I have a dictionary where the value is a Dictionary<string, Object>.

I am looking for a solution for merging tow Dictionary<string, Dictionary<string, Object>>, with the following requirements:

Upvotes: 3

Views: 1420

Answers (4)

pescolino
pescolino

Reputation: 3123

The first question you should ask yourself: What type does the result of merging two dictionaries have? How can values be merged together if they share the same key?

It could be something like this:

public static Dictionary<TKey, IEnumerable<TValue>> Merge<TKey, TValue>(this IDictionary<TKey, TValue> this_, IDictionary<TKey, TValue> other)
{
    return this_.Concat(other).     // IEnumerable<KeyValuePair<TKey, TValue>>
        GroupBy(kvp => kvp.Key).    // grouped by the keys
        ToDictionary(grp => grp.Key, grp => grp.Select(kvp => kvp.Value).Distinct());
}

So your two dictionaries of type Dictionary<string, Dictionary<string, object>> will go to a Dictionary<string, IEnumerable<Dictionary<string, object>>>.

However, your values are dictionaries so you might want to merge them:

public static Dictionary<TKey, IEnumerable<TValue>> Flatten<TKey, TValue>(IEnumerable<Dictionary<TKey, TValue>> dictionaries)
{
    return dictionaries.SelectMany(d => d.Keys).Distinct().         // IEnumerable<TKey> containing all the keys
        ToDictionary(key => key,
            key => dictionaries.Where(d => d.ContainsKey(key)).     // find Dictionaries that contain the key
                Select(d => d.First(kvp => kvp.Key.Equals(key))).   // select that key (KeyValuePair<TKey, TValue>)
                Select(kvp => kvp.Value));                          // and the value
}

This takes an IEnumerable<Dictionary<string, object>> and transforms it into a Dictionary<string, IEnumerable<object>>. You can now call this method for each value of the dictionary that Merge produced.

The calls would be:

Dictionary<string, IEnumerable<Dictionary<string, object>>> result1 = dic1.Merge(dic2);
Dictionary<string, Dictionary<string, IEnumerable<object>>> result2 = dic1.Merge(dic2).ToDictionary(kvp => kvp.Key, kvp => Flatten(kvp.Value));

Upvotes: 0

Ks_Hamza
Ks_Hamza

Reputation: 81

 internal static Dictionary<string, Dictionary<string, object>> OperationDic(Dictionary<string, Dictionary<string, object>> a, Dictionary<string, Dictionary<string, object>> b, string operation)
    {
        var result = new Dictionary<string, Dictionary<string, object>>(a);
        switch (operation)
        {
            case "+":                  
            // now check to see if we can add stuff from b
            foreach (var entryOuter in b)
            {
              Dictionary<string, object> existingValue;
              if (result.TryGetValue(entryOuter.Key, out existingValue))
              {
                  Dictionary<string, object> Value = entryOuter.Value;
                  result[entryOuter.Key] = existingValue.Concat(Value).GroupBy(d => d.Key).ToDictionary(d => d.Key, d => d.First().Value);
              }
              else
              {
                // new entry
                result.Add(entryOuter.Key, entryOuter.Value);
              }
            }
            return result;
            default:                    
                throw new Exception("FAIL ...");
        }
    }

Upvotes: 0

Jeppe Stig Nielsen
Jeppe Stig Nielsen

Reputation: 61952

It's not very clear to me what you want. This tries to merge the two dictionaries:

    // first copy everything from a
    var result = new Dictionary<string, Dictionary<string, object>>(a);

    // now check to see if we can add stuff from b
    foreach (var entryOuter in b)
    {
      Dictionary<string, object> existingValue;
      if (result.TryGetValue(entryOuter.Key, out existingValue))
      {
        // there's already an entry, see if we can add to it
        foreach (var entryInner in entryOuter.Value)
        {
          if (existingValue.ContainsKey(entryInner.Key))
            throw new Exception("How can I merge two objects? Giving up.");
          existingValue.Add(entryInner.Key, entryInner.Value);
        }
      }
      else
      {
        // new entry
        result.Add(entryOuter.Key, entryOuter.Value);
      }
    }

    return result;

You might want to add checks for null. a, b, and existingValue (when it exists) may be null.

Upvotes: 1

Hella Nouaouri
Hella Nouaouri

Reputation: 1

try this

var result = a.Concat(b).GroupBy(c => c.Key).ToDictionary>(

Upvotes: 0

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