Adding running sum in group by date in new row

Question

I'm working Syncfusion DocIO with creating tables in .docx with some props and can't create row with group by date => on every new year I need new row with running sum. I already create sum row, but this row returns all sum for additional props (columns), so all I need is for each year in new row running sum.

My example:

Months	Anuity	InterestPaid	PrincipalPaid	BalanceDue	Date
1	84,69	2,50	82,19	917,81	2021/11/12
2	84,69	2,29	82,40	835,41	2021/12/12
Sum for year 2021
3	84,69	2,09	82,61	752,80	2022/1/12
4	84,69	1,88	82,81	669,99	2022/2/12
5	84,69	1,67	83,02	586,97	2022/3/12
6	84,69	1,47	83,23	503,75	2022/4/12
7	84,69	1,26	83,43	420,31	2022/5/12
8	84,69	1,05	83,64	336,67	2022/6/12
9	84,69	0,84	83,85	252,82	2022/7/12
10	84,69	0,63	84,06	168,75	2022/8/12
11	84,69	0,42	84,27	84,48	2022/9/12
12	84,69	0,21	84,48	0,00	2022/10/12
Sum for year 2022
Sum all	1016,32	16,32	1000,00

My code:

        int i = 1;
        
        foreach (var amortizationData in aAmortizationPlanLoanPayment)
        {
            WTableRow tableRow = tableAmortizationData.AddRow(true);

            tableRow.Cells[0].AddParagraph().AppendText(i.ToString());
            tableRow.Cells[1].AddParagraph().AppendText(amortizationData.Anuity.ToString());
            tableRow.Cells[2].AddParagraph().AppendText(amortizationData.InterestPaid.ToString());
            tableRow.Cells[3].AddParagraph().AppendText(amortizationData.PrincipalPaid.ToString());
            tableRow.Cells[4].AddParagraph().AppendText(amortizationData.BalanceDue.ToString());
            tableRow.Cells[5].AddParagraph().AppendText(amortizationData.Date.AddMonths(aAmortizationPlanLoanPaymentData.Moratorium).ToString("yyyy/M/dd"));
            i++;
            
            if (amortizationData.Date.Month == 12)
            {
                    WTableRow YearSumrow = tableAmortizationData.AddRow(true);

                    WTableCell cell1 = YearSumrow.Cells[0];

                    var sumYearIWTextRange = cell1.AddParagraph().AppendText($"Sum for year {amortizationData.Date.Year}");

                sumYearIWTextRange = YearSumrow.Cells[1].AddParagraph().AppendText(); // need here running sum inside appendText();

                sumYearIWTextRange = YearSumrow.Cells[2].AddParagraph().AppendText(); // need here running sum inside appendText();

                sumYearIWTextRange = YearSumrow.Cells[3].AddParagraph().AppendText(); // need here running sum inside appendText();
            }

            if (amortizationData.BalanceDue == 0.00)
            {
                WTableRow LastYearRow = tableAmortizationData.AddRow(true);

                WTableCell cellLastYear = LastYearRow.Cells[0];

                var sumLastYearIWTextRange = cellLastYear.AddParagraph().AppendText($"Sum for year {amortizationData.Date.Year}");

                sumLastYearIWTextRange = LastYearRow.Cells[1].AddParagraph().AppendText(); // need here running sum inside appendText();

                sumLastYearIWTextRange = LastYearRow.Cells[2].AddParagraph().AppendText(); // need here running sum inside appendText();

                sumLastYearIWTextRange = LastYearRow.Cells[3].AddParagraph().AppendText(); // need here running sum inside appendText();
            }
        }

        
        WTableRow tableRowSum = tableAmortizationData.AddRow(true);
        WTableCell cell = tableRowSum.Cells[0];

        var totalIWTextRage = cell.AddParagraph().AppendText("Sum all");

        var totalAmountIWTextRage = tableRowSum.Cells[1].AddParagraph().AppendText(aAmortizationPlanLoanPayment.Sum(p => p.Anuity).ToString());

        totalAmountIWTextRage = tableRowSum.Cells[2].AddParagraph().AppendText(aAmortizationPlanLoanPayment.Sum(p => p.InterestPaid).ToString());

        totalAmountIWTextRage = tableRowSum.Cells[3].AddParagraph().AppendText(aAmortizationPlanLoanPayment.Sum(p => p.PrincipalPaid).ToString());

Answer 1

If you had a bunch of numbers (already grouped and summed to distinct dates, but doesn't have to be);

(DateTime D, int V)[] rows = new [] {
  (new(1999, 12, 1), 111), 
  (new(2000, 1, 1), 222), 
  (new(2000, 2, 1), 333), 
  (new(2000, 3, 1), 444),
  (new(2001, 1, 1), 555)
}

Then sure, you could do your running sum with LINQ:

foreach(var row in rows){
  var runSum = rows.Where(r => r.D <= row.D).Sum(r => r.V);
}

But it's a lot more resource wasteful than just keeping a variable:

var runSum = 0;
foreach(var row in rows){
  runSum += row.V;
}

If you want your running sum to start over from time to time just remember the previous row (naturally your rows need to be in order):

var prevRow = rows[0];
var runSum = 0;
foreach(var row in rows){

  if(prevRow.D.Year != row.D.Year)
    runSum = 0;

  runSum += row.V;
}

Do your output above the line where you increment the runSum if you don't want the current line value to appear in the total, or below it if you do