Steema Central

Posted: **Wed Apr 09, 2025 7:38 pm**

D12.2, TChart 24.42
In a chart I needed, I could not get a stacked area chart to work, so I add the values of previous series to the new series point. Also, when a value goes to zero, I step it down, so that the chart goes straight to zero.

The chart works fine when I don't use decimal values:

But when I add decimals, it adds a second step down in the 20th year, and appears incorrectly:

The step down code is something I got from Steema years ago (a bit modified).

The attached demo reproduces this--simply check/uncheck the "Include Decimals" checkbox.

How do I avoid the problem with the second chart?

Thank you,

Ed Dressel

Posted: **Fri Apr 11, 2025 11:06 am**

Hello,

Looking at the final data in the series I see at the index 18, instead of reusing the preceding value (index 17), it takes the value of a couple of indices above (index 15):

: JFKUAgWmmP.png (79.73 KiB) Viewed 4490 times

If you debug the final lChartStepDowns loop, where you add the repeated values, you'll see you are getting the stepDowns for values 8, 5 and 15, in that order.
- Adding a repeated value for the 8 affects the indexes >8. Ok.
- Adding a repeated value for the 5 affects the indexes >5. The operation above didn't affect this. Ok.
- Adding a repeated value for the 15 affects the indexes >15. The operations above affect this because now at the index 15 you have the XValue 13 and YValue 11.627.45.

To fix this, you only have to sort the lChartStepDowns before the loop so you add repeated loops from the end:

Code: Select all

uses Generics.Defaults;

var IntegerComparer: IComparer<Integer>;

function CompareStepDowns(const ALeft, ARight: TChartStepDown): Integer;
begin
  Result:=IntegerComparer.Compare(ALeft.FX, ARight.FX);
end;

procedure TForm2.UpdateChart(aChart: TChart);
//...
var
  Comparer: IComparer<TChartStepDown>;
  //...
    Comparer:=TComparer<TChartStepDown>.Construct(CompareStepDowns);
    lChartStepDowns.Sort(Comparer);

    for I := lChartStepDowns.Count-1 downto 0 do begin
      lChartStepDown := lChartStepDowns[I];
      //...
end;

Posted: **Fri Apr 11, 2025 2:09 pm**

Thank you! That works perfectly.

Steema Central

Chart shows a dip when including decimals

Chart shows a dip when including decimals

Re: Chart shows a dip when including decimals

Re: Chart shows a dip when including decimals