Make single events visible in long line charts

[bfrost]

Sorry if this has been asked before but I have a need to ensure that when display a line chart of many similar points (eg 10,000 points of say value = 100) that a single different numeric event (say value = 0) is visible even when looking at the entire chart as well as when zoomed in. It seems to me that this must be a common requirement when assessing chart data visually for issues. Can I implement this easily?
Regards,
Brian

[SteveP]

Using a LineSeries with Ver 7.04, I see the single different data value no matter what size the chart's form is. There are options for faster plotting the use different methods of decimation that may or may not show the single different value.

for i := 1 to 10000 do series1.AddY(100);
series1.YValue[5000] := 0;

[Narcís]

Hi Brian,

Yes, this can be easily achieved. Just place a TChart on a form and add a TLineSeries to it, do following code will do the rest. You'll easily see the point at (5000, -100) and this will be visible when zooming that area.

Code: Select all

procedure TForm1.FormCreate(Sender: TObject);
var
  i: Integer;
begin
  Chart1.View3D:=False;
  Randomize;

  With Series1 do
  begin
    for i:=0 to 10000 do Add(random*100);
    AddXY(5000,-100);
    Pointer.Visible:=True;
  end;
end;