Addition on HashSet of KeyValuePair

Question

I have a list of entries. Each entry contains a string and a numerical value. The same string can appear one or more times in a list and it can have a different numerical value. be I am looking for an elegant way to process the list. The end result should be a list of unique pairs of string and (sum of values for the string). Each unique string should be associated with the sum of all numerical values for the string. I consider creating a HashSet<KeyValuePair<string, double>> and to add each string to the HashSet. But I am not sure how to add all values together in a single loop. The code below works, but it is inefficient.

        SortedSet<string> symbols = new SortedSet<string>();
        HashSet<KeyValuePair<string, double>> results = new HashSet<KeyValuePair<string, double>>();
        string file = openFileDialog1.FileName;
        string[] lines = File.ReadAllLines(file);
        
        foreach(string line in lines) {
            string[] values = line.Split('\t');
            string symbol = values[0].Trim();
            symbols.Add(symbol);
        }
        
        foreach(string uniqueSymbol in symbols) {
            double value = 0;
            foreach(string line in lines) {
                string[] values = line.Split('\t');
                string symbol = values[0].Trim();
                string sProfit = values[7].Trim();
                double fProfit = Convert.ToDouble(sProfit);
                
                if(symbol == uniqueSymbol) {
                    value += fProfit;
                }
            }
            
            results.Add(new KeyValuePair<string, double>(uniqueSymbol, value));
        }

Answer 1

As several others here, I agree that a Dictionary sounds like what suits your needs best. If using Linq is an option, here is an apporach that should work:

Dictionary<string, double> results = lines
    .Select(line => line.Split('\t'))
    .Select(lineEntries => (
        Symbol: lineEntries[0].Trim(), 
        Value: Convert.ToDouble(lineEntries[7].Trim()))) // Some validation should be done here
    .GroupBy(symbolAndValue => symbolAndValue.Symbol)
    .ToDictionary(
        gr => gr.Key,
        gr => gr.Select(symbolAndValue => symbolAndValue.Value).Sum());

I'm creating a tuple (string Symbol, double Value) for each line, then grouping them by Symbol, then creating a dictionary using Symbol as the Key and the sum of values connected to Symbol as the Value for each dictionary entry.

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A slightly more concise approach would be merging the two Select statements together by performing line.Split('\t') twice:

.Select(line => (
    Symbol: line.Split('\t')[0].Trim(), 
    Value: Convert.ToDouble(line.Split('\t')[7].Trim())))