How do I combine two dictionaries

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I have two dictionaries D1 and D2 as follows

VB

Dim D1 As New Dictionary(Of String, String)
Dim D2 As New Dictionary(Of String, String)

I want to combine these two dictionaries into one new dictionary as follows:

VB

Dim D3 As New Dictionary(Of String, String)
D3 = D1.Union(D2)

But I get error! Any help? Notice that there is no duplicate in the keys

What I have tried:

I can find many examples but for C# not for VB.net

Posted 20-Nov-16 21:41pm

Member 12789975

Updated 20-Nov-16 22:31pm

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Afzaal Ahmad Zeeshan 21-Nov-16 3:48am

What error?

2 solutions

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OriginalGriff · Accepted Answer · 2016-11-20T22:31:00

Solution 1

Union does not return a Dictionary, it returns an IEnumerable.
If you need a Dictionary, you need to use ToDictionary to convert it:

VB

Dim D1 As New Dictionary(Of String, String)()
Dim D2 As New Dictionary(Of String, String)()
...
Dim D3 As Dictionary(Of String, String) = D1.Union(D2).ToDictionary(Function(p) p.Key, Function(p) p.Value)

Posted 20-Nov-16 22:31pm

OriginalGriff

Comments

Andy Lanng 21-Nov-16 4:33am

Dammit Griff! Always beat me by seconds :Þ

OriginalGriff 21-Nov-16 4:43am

Sorry! Have an upvote as compensation!

Andy Lanng 21-Nov-16 8:33am

^_^

Andy Lanng · Accepted Answer · 2016-11-20T22:31:00

The linq extensions work on IEnumerable objects. A dictionary is IEnumerable<keyvaluepair>. It will also return the IEnumerable type.

This being the case, you need to create a dictionary out of the ienumerable. Fortunatly, there is an extension for this, too.

Enumerable.ToDictionary(TSource, TKey) Method (IEnumerable(TSource), Func(TSource, TKey)) (System.Linq)[^]

C#:

C#

D3 = D1.Union(D2).ToDictionary(d=>d.Key, d=>d.Value)

VB:

VB

D3 = D1.Union(D2).ToDictionary(Function(d) d.Key, Function(d) d.Value)

Hope that helps ^_^
Andy