group by on dictionary with custome class key,value objects using linq - linq

Question

I have a requirement where i have to do a group by on the dictionary and get the resulting rows on the basis of a group by into another dictionary having key,value pair , value being a List(Positions).
Here is the below code snippet which explains my problem statement:
public class Positions
{
public string Value1 { get; set; }
public int Value2 { get; set; }
public string Value3 { get; set; }
public string Value4 { get; set; }
public string Value5 { get; set; }
public string Value6 { get; set; }
public string Value7 { get; set; }
public string Value8 { get; set; }
public string Value9 { get; set; }
public string Value10 { get; set; }
public string Value11 { get; set; }
public string Value12 { get; set; }
}
public struct PositionKey
{
public string Value1 { get; set; }
public int Value2 { get; set; }
public string Value3 { get; set; }
public string Value4 { get; set; }
public string Value5 { get; set; }
public string Value6 { get; set; }
public override int GetHashCode()
{
return (Value1 != null ? Value1.GetHashCode() : 1)
^ (Value2 > 0 ? Value2.GetHashCode() : 1)
^ (Value3 != null ? Value3.GetHashCode() : 1)
^ (Value4 != null ? Value4.GetHashCode() : 1)
^ (Value5 != null ? Value5.GetHashCode() : 1)
^ (Value6 != null ? Value6.GetHashCode() : 1);
}
public override bool Equals(object obj)
{
PositionKey compositeKey = (PositionKey)obj;
return Value1 == compositeKey.Value1
&& Value2 == compositeKey.Value2
&& Value3 == compositeKey.Value3
&& Value4 == compositeKey.Value4
&& Value5 == compositeKey.Value5
&& Value6 == compositeKey.Value6;
}
}
public struct GroupbyPositionKey
{
public string Value1 { get; set; }
public int Value2 { get; set; }
public override int GetHashCode()
{
return (Value1 != null ? Value1.GetHashCode() : 1)
^ (Value2 > 0 ? Value2.GetHashCode() : 1);
}
public override bool Equals(object obj)
{
PositionKey compositeKey = (PositionKey)obj;
return Value1 == compositeKey.Value1
&& Value2 == compositeKey.Value2;
}
}
public class program
{
/*
Value1 Value2 Value3 Value4 Value5 Value6 Value7 Value8 Value9 Value10 Value11 Value12
-------------------------------------------------------------------------------------------------
v1 1 val1 val2 val3 val4 val5 val6 val7 val8 val9 val10
v1 1 val2 val3 val4 val5 val6 val7 val8 val9 val10 val11
v3 4 val3 val4 val5 val6 val7 val8 val9 val10 val11 val12
v3 4 val4 val5 val6 val7 val8 val9 val10 val11 val12 val13
v3 5 val5 val6 val7 val8 val9 val10 val11 val12 val13 val14
v4 6 val6 val7 val8 val9 val10 val11 val12 val13 val14 val15
v4 6 val7 val8 val9 val10 val11 val12 val13 val14 val15 val16
v4 7 val8 val9 val10 val11 val12 val13 val14 val15 val16 val17
v4 7 val9 val10 val11 val12 val13 val14 val15 val16 val17 val18
Group by - Value1 Value2 Value3 Value4 Value5 Value6 Value7 Value8 Value9 Value10 Value11 Value12
Get List of the rows after the grouping on the basis of group by Value1,Value2
*/
public static void main()
{
Dictionary<PositionKey, Positions> dictPositons = new Dictionary<PositionKey, Positions>();
Positions obj = new Positions();
obj.Value1 = "v1";
obj.Value2 = 1;
obj.Value3 = "val1";
obj.Value4 = "val2";
obj.Value5 = "val3";
obj.Value6 = "val4";
obj.Value7 = "val5";
// ........ and so on.. and so forth...for all the objects.
/*
I have a datatable as above and i am inserting the rows in the collection object of class <Positions> with respective key
and add the same to the dictionary.
*/
PositionKey key = new PositionKey();
key.Value1 = "v1";
key.Value2 = 1;
key.Value3 = "val3";
key.Value4 = "val4";
key.Value5 = "val5";
key.Value6 = "val6";
if (!dictPositons.ContainsKey(key))
{
dictPositons.Add(key, obj); // this dictionary would have the raw data which would have all the rows from the table as a dictionary collection
}
/*
Now I have to create another dictionary which gives me a list of all the records by grouping on the basis
of the key <GroupbyPositionKey> which is nothing but <Value1,Value2>
The resulting dictionary should look like Dictionary<GroupbyPositionKey,List<Positions>>
*/
Dictionary<GroupbyPositionKey, List<Positions>> result = new Dictionary<GroupbyPositionKey, List<Positions>>();
result = dictPositions.GroupBy(....); // not sure how ?
}
}
In the result i would want to have another dictionary with the key object with value1,value2 and value object as List(Positions). I am not sure how to approach the group by in the dictionary to get the desired result.
I have already achieved this result by looping through the dictionary manually and then pick and insert into the other dictionary on the basis of new key. But i wanted to know if there is a LINQ way of doing this which is going to be much shorter.

Answer 1

Within your GroupBy statement, you will need to create a new GroupbyPositionKey class and then use the ToDictionary method to select your key and the list
Dictionary<GroupbyPositionKey, List<Positions>> result = dictPositons
.GroupBy(x => new GroupbyPositionKey { Value1 = x.Key.Value1, Value2 = x.Key.Value2 })
.ToDictionary(x => x.Key, x => x.Select(y => y.Value).ToList());