Count duplicated items in array

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I'm trying to extract AutoCAD attribute block to excel

Excel Output[^]

My question is how to count duplicated items in array and add them to new column

What I have tried:

List<object[]> rooms = new List<object[]>();
            using (var tr = db.TransactionManager.StartTransaction())
            {
                foreach (SelectedObject so in psr.Value)
                {
                    BlockReference bref = (BlockReference)tr.GetObject(so.ObjectId, OpenMode.ForRead);                    
                    Autodesk.AutoCAD.DatabaseServices.AttributeCollection attcoll = bref.AttributeCollection;
                    object[] info = new object[4];
                    foreach (ObjectId id in attcoll)
                    {
                        AttributeReference atref = (AttributeReference)tr.GetObject(id, OpenMode.ForRead);

                        if (atref.Tag=="ROOM")
                        {
                            info[0] = atref.TextString;
                        }
                        if (atref.Tag=="ROOMID")
                        {
                            info[1] = atref.TextString;
                        }
                        if (atref.Tag=="ROOMAREA")
                        {
                            info[2] = atref.TextString;
                        }

                        if (!rooms.Contains(info))
                        {
                            rooms.Add(info);
                        }
                    }
                }
                tr.Commit();
            }

Posted 21-Feb-18 2:40am

Mohamed Ahmed

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BillWoodruff 21-Feb-18 10:27am

I don't see anything in your code that "counts." Define clearly what a "duplicate" is here.

1 solution

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Maciej Los · Answer 1 · 2018-02-21T06:05:00

Solution 1

Instead of List<object[]> i'd use a Dictionary[^].

C#

Dictionary<string, int> myCounter = new Dictionary<string, int>();
using (var tr = db.TransactionManager.StartTransaction())
{
    foreach (SelectedObject so in psr.Value)
    {
        BlockReference bref = (BlockReference)tr.GetObject(so.ObjectId, OpenMode.ForRead);                    
        Autodesk.AutoCAD.DatabaseServices.AttributeCollection attcoll = bref.AttributeCollection;
        foreach (ObjectId id in attcoll)
        {
            AttributeReference atref = (AttributeReference)tr.GetObject(id, OpenMode.ForRead);
            if (atref.Tag.Contains("ROOM"))
                if (!myCounter.ContainsKey(atref.TextString))
                {
                    myCounter.Add(atref.TextString, 1);
                }
                else
                {
                    myCounter[atref.TextString] += 1; 
                }
        }
    }
}

//Dictionary object contains unique data with the number of occurences
Console.WriteLine("Key | Count");
foreach(var k in myCounter.Keys)
{
	Console.WriteLine("{0} | {1}", k, myCounter[k]);
}

Above code should return something like this:

Key | Count
ROOM | 5
ROOMID | 10
ROOMAREA | 15

Posted 21-Feb-18 6:05am

Maciej Los

Updated 21-Feb-18 6:07am

v2

Comments

#realJSOP 21-Feb-18 13:20pm

If you used a HashSet, you wouldn't need the line

if (!myCounter.ContainsKey(atref.TextString))

Trying to add an item that already exists in the HashSet collection would be ignored (without an exception being generated).

Maciej Los 21-Feb-18 13:29pm

Good point!
Thank you, John. I'll use it next time ;)

[EDIT]
I've been trying to implement HashSet<CustomClass(Name, Count)> with IEqualityComparer<CustomClass>, but it does not satisfy me, because comparing objects by its name does not enables to increase count.

#realJSOP 21-Feb-18 14:21pm

Why can't you use Linq to get the count of unique items within the collection?

Matt T Heffron 21-Feb-18 13:36pm

But a HashSet won't give the count.
It is approximately equivalent to Dictionary<T, bool> but if the key is present the bool value is always true.
(Or am I missing something... ?)

Maciej Los 21-Feb-18 13:39pm

Matt, maybe John wanted to point me to Hashtable :)
[EDIT]
Maybe not ;(
Hastable throws an error when key already exists.

#realJSOP 21-Feb-18 14:15pm

HashSet does have a Count property. In the past, I used a HashSet to count unique colors in an image. I even posted a tip/trick about it.

https://www.codeproject.com/Tips/159307/Count-Number-of-Unique-Colors-in-an-Image

I specifically used a HashSet because it didn't throw exceptions when trying to add a duplicate item.

Maciej Los 21-Feb-18 14:19pm

As i mentioned, i've created CustomClass with two members(properties): Name & Count. I wanted to achieve the same as above. If Key exists, increase Count.
I'll follow your trick.

Maciej Los 21-Feb-18 14:24pm

Seems, that OP's requirement is different. If i understand it well OP want to count duplicated items. Using Dictionary i can enumerate all items and return the count of each item in a dictionary.

Matt T Heffron 21-Feb-18 17:45pm

Maciej,
To get the counts of each key, without needing the explicit .ContainsKey() test you could use the somewhat obscure class System.Collections.Concurrent.ConcurrentDictionary<TKey,TValue>
In your example changing Dictionary<string,int> to be ConcurrentDictionary<string,int> the whole

if (!myCounter.ContainsKey(atref.TextString)){  myCounter.Add(atref.TextString, 1);}else{  myCounter[atref.TextString] += 1}

collapses to the single statement:

myCounter.AddOrUpdate(atref.TextString, 1, (k,v) => v + 1);

Of course, this comes with the cost of concurrency protection overhead that isn't necessary.

Matt T Heffron 21-Feb-18 17:22pm

John, Maciej's example had the count of number of duplicates for each key. The .Count property of HashSet is the number of entries in the collection, so it is the number of keys. (Not even the number of keys that have duplicates.)