CODEWITHSUNDEEP
c#.net
moisesvega
moisesvega

Reputation: 445

Can I compare the keys of two dictionaries?

Using C#, I want to compare two dictionaries to be specific, two dictionaries with the same keys but not same values, I found a method Comparer but I'm not quite sure how can I use it? Is there a way other than iterating through each key?

Dictionary
[
    {key : value}
]

Dictionary1
[
    {key : value2}
]

Upvotes: 16

Views: 24878

Answers (7)

Jaswant Agarwal
Jaswant Agarwal

Reputation: 4915

I think this is fastest way to check the differences between keys apart from count.

var isTrue = !dict1.Keys.Any(k => !dict2.Keys.Contains(k)) &&
                         !dict2.Keys.Any(k => !dict1.Keys.Contains(k));

Upvotes: 0

Branko Dimitrijevic
Branko Dimitrijevic

Reputation: 52157

You could just:

new HashSet<TKey>(dictionary1.Keys).SetEquals(dictionary2.Keys)

Be careful if dictionary1 uses a different comparer from dictionary2. You'll have to decide whether "equality" means what one or the other dictionary thinks it means (or something else entirely)...

Upvotes: 0

Андрей Ивойлов
Андрей Ивойлов

Reputation: 111

return dict1.Count == dict2.Count && 
       dict1.Keys.All(dict2.ContainsKey);

Upvotes: 11

codeandcloud
codeandcloud

Reputation: 55333

Try this

public bool SameKeys<TKey, TValue>(IDictionary<TKey, TValue> one, IDictionary<TKey, TValue> two)
{
    if (one.Count != two.Count) 
        return false;
    foreach (var key in one.Keys)
    {
        if (!two.ContainsKey(key))
            return false;
    }
    return true;
}

Upvotes: 1

vcsjones
vcsjones

Reputation: 141703

If all you want to do is see if the keys are different but not know what they are, you can use the SequenceEqual extension method on the Keys property of each dictionary:

Dictionary<string,string> dictionary1;
Dictionary<string,string> dictionary2;
var same = dictionary1.Count == dictionary2.Count && dictionary1.Keys.SequenceEqual(dictionary2.Keys);

If you want the actual differences, something like this:

var keysDictionary1HasThat2DoesNot = dictionary1.Keys.Except(dictionary2.Keys);
var keysDictionary2HasThat1DoesNot = dictionary2.Keys.Except(dictionary1.Keys);

Upvotes: 27

Tipx
Tipx

Reputation: 7515

You could go with this (depending if you want the intersect or the exclusion):

Dictionary<int, int> dict1 = new Dictionary<int, int>();
Dictionary<int, int> dict2 = new Dictionary<int, int>();

IEnumerable<int> keys1ExceptKeys2 = dict1.Keys.Except(dict2.Keys);
IEnumerable<int> keys2ExceptKeys1 = dict2.Keys.Except(dict1.Keys);
IEnumerable<int> keysIntersect = dict1.Keys.Intersect(dict2.Keys);

Upvotes: 0

MGZero
MGZero

Reputation: 5982

You can get a collection of the keys and index it, if that helps.

dictionary1.keys[0] == dictionary2.keys[5]

I'm actually not sure if you index it with a number or if you do it with the key itself, so try out both.

Upvotes: 0

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