Adding/updating concurrentDictionary<string,int[]> issues

Question

Hey everyone:

I have the following code, but am stuck at the point in the code where I have the comments. I'm having difficulty trying to figure out how to add a value to a specified index in an integer array within a concurrent dictionary if the key doesn't yet exist; or update the value if the key in the concurrentdictionary already exists.

How do I do this?

Thanks!

            int intCount = 0;
            string[] arrFirstFileCombos;
            string[] arrSecondFileCombos;
            ConcurrentDictionary<string, int[]> arrCombosAndMatches;
            arrFirstFileCombos = File.ReadAllLines(strCompareFirstFile);
            arrSecondFileCombos = File.ReadAllLines(strCompareSecondFile);
            if (arrFirstFileCombos.Length > arrSecondFileCombos.Length)
            {
                arrCombosAndMatches = new ConcurrentDictionary<string, int[]>(poParallelOptions.MaxDegreeOfParallelism, arrFirstFileCombos.Length);
            }
            else
            {
                arrCombosAndMatches = new ConcurrentDictionary<string, int[]>(poParallelOptions.MaxDegreeOfParallelism, arrSecondFileCombos.Length);
            }
            Parallel.For(0, arrFirstFileCombos.Length, poParallelOptions, x =>
            {
                Parallel.ForEach(arrSecondFileCombos, poParallelOptions, v2 =>
                {
                    int intNumberSame = 0;
                    string[] arrTemp = v2.Trim().Split(charArrComma);
                    for (int t = 0; t < arrTemp.Length; t++)
                    {
                        intNumberSame += substr_count(arrFirstFileCombos[x].Trim(), arrTemp[t]);
                    }
                    //Here I want to:
                    //1) add v2 to arrCombosAndMatches if it doesn't yet exist with the value 1 in the intNumberSame index.
                    //2) update the intNumberSame index in the v2 key with its current value + 1 if v2 does exist in arrCombosAndMatches
                });
            });

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Answer 1

Just spent 20 minutes on this one but didn't test, here's a possible pattern:

 Parallel.ForEach(arrSecondFileCombos, poParallelOptions, v2 =>
                {
                    int intNumberSame = 0;
                    string[] arrTemp = v2.Trim().Split(charArrComma);
                    for (int t = 0; t < arrTemp.Length; t++)
                    {
                        intNumberSame += substr_count(arrFirstFileCombos[x].Trim(), arrTemp[t]);
                    }
                    //Here I want to:
                    //1) add v2 to arrCombosAndMatches if it doesn't yet exist with the value 1 in the intNumberSame index.
                    var exist = from q in arrCombosAndMatches
                                where q.Key.Contains(v2)
                                select q.Key;
                    if(!exist.Count==1) arrCombosAndMatches.TryAdd(exist, v2);
                    //2) update the intNumberSame index in the v2 key with its current value + 1 if v2 does exist in arrCombosAndMatches
                });

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JP Cowboy Coders Unite!

Answer 2

Check if this works:

arrCombosAndMatches
         .AddOrUpdate( v2,
                       k =>
                       {
                           var a = new int[intNumberSame + 1];
                           a[intNumberSame] = 1;
                           return a;
                       },
                       ( k, a ) =>
                       {
                           if( a.Length <= intNumberSame ) Array.Resize( ref a, intNumberSame + 1 );
                           ++a[intNumberSame];
                           return a;
                       } );

Maybe it is better to use a Dictionary of Dictionaries rather than Dictionary if Array.

Answer 3

Please use this forum: http://social.msdn.microsoft.com/Forums/en-US/parallelextensions/threads

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Mike Zhang[MSFT]
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