TAChart - add, but "inside" the other series
lazarus / 55-TAChart

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Nicole · 2022-09-30 13:26

We have a TAChart, which's series are added at runtime by

Series.AddXY(xx,yy);
Series.AddXY(date,o,h,l,c)
etc.

Those series have all in common: The x-axes, which contains the date.

Now I ADD one more series after the others are added already.
It is added nicely, - on the right side of the existing series, with a
double populated x-aches.

How can I say,
"add some y values to the existing(!) x-axes date"?

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wp · 2022-09-30 14:06

Show your code.

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Nicole · 2022-09-30 14:38

What the code does (many bugs and typos to do, pls do not tell me, I
know it):

Pls mind the fk1 or fk2 or fk3.
fk for "foreign key" are the keys to SQL-series.
The first query takes 3 SQL-series in one request.

In the second query takes only 1 SQL-seried for fk1 and shall draw the
candlestick-chart-series.
The second series ("inside") is added after the German comment, which
reads
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i "  //
zweite Query wird gestaltet, die den Kontrakt 1 ins Chart zeichnet"
Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i procedure
TFrame_oi.Zeichne_oi(fk1, fk2, fk3: integer);Var s: string;   
openinterest, volumen: integer;    Baranzahl: integer;//    kontrak1,
kontrak2, kontrakt3: TEinKontrakt;    dat, dat_alt, dat2, dat1:
TDateTime;    d: double; begin 
Baranzahl:=StrToInt(LabeledEdit_oiBaranzahl.Caption); 
dat2:=DB_Kontrakte.ReadSQL_tbKontrakteLetztesDatum(now); // dat2 ist
das letzte verfügbare Datum  dat1:=IncDay(dat2, - Baranzahl);   // 20
Tage sind ca 1 Monat, dat 1 = erstes einzulesendes Datum 
dat_alt:=dat1;    if fk1 <> -1 then     s:=
DB_Kontrakte.ReadSQL_tbKontrakteElementZuID(fk1, 'NAME_'); 
Chart_oi.Title.Text.Text:='Liquidität der Kontrkate um ' + s + ' //
Volumen ► blau, oi ► rot, ratio ► fett (linke Skala)';  // fett ging
nicht mit <b>ratio</b>  if fk3 = -1   // mit den anderen beiden müsste
ich die Ware abfragen  then showMessage('Frame_oi.Zeichne_oi damit
habe ich noch wenig Erfahrung, hier fehlt jedenfalls der 3.
Fremdschüssel');   s:='Select FK_JDATUM, VOLUME, openinterest From
TBKURSZEILEN A ' +      'where FK_JDATUM > :datum '+      'and
(FK_KONTRAKT = :fk1 or FK_KONTRAKT = :fk2 or FK_KONTRAKT = :fk3) ' + 
    'order by fk_JDatum ';  // wenn eines davon -1 wäre Abbruch 
IBQuery_oi.SQL.Text:=s;            // die id der 3 Kontrakte und das
Datum  IBQuery_oi.ParamByName('datum').AsDate:=dat1; 
IBQuery_oi.ParamByName('fk1').AsInteger:=fk1; 
IBQuery_oi.ParamByName('fk2').AsInteger:=fk2; 
IBQuery_oi.ParamByName('fk3').AsInteger:=fk3;  
IBQuery_oi.Active:=true;   Chart_oiLineSeries_oi.Clear; 
Chart_oiLineSeries_vol.Clear;  Chart_oiLineSeries_ratio.Clear; 
openinterest:=0;  volumen:=0;  while not IBQuery_oi.EOF do begin //
openinterest und volumen werden aus allen 3 Kontrakten addiert    
dat:=IBQuery_oi.FieldByName('FK_JDATUM').AsDateTime;    if dat=dat_alt
then begin        openinterest:=openinterest +
IBQuery_oi.FieldByName('openinterest').AsInteger;       
volumen:=volumen + IBQuery_oi.FieldByName('VOLUME').AsInteger;    end 
  else begin        //  die vorigen Werte werden gezeichnet        if
volumen <> 0 then begin          Chart_oiLineSeries_oi.AddXY(dat,
openinterest);          Chart_oiLineSeries_vol.AddXY(dat, volumen);  
//      Chart_oi_Candles.AddXOHLC(date,o,h,l,c);         
d:=openinterest / volumen;         
Chart_oiLineSeries_ratio.AddXY(dat, d);        end;        
dat_alt:=dat;  // es wird neu gerechnet und neu zugewiesen       
openinterest:=IBQuery_oi.FieldByName('openinterest').AsInteger;      
volumen:=IBQuery_oi.FieldByName('VOLUME').AsInteger;    end;    
IBQuery_oi.Next;  end;   // zweite Query wird gestaltet, die den
Kontrakt 1 ins Chart zeichnet  IBQuery_oiEinKontrakt.SQL.Text:='Select
first 50 ID_KURSZEILEN, FK_JDATUM, FK_KONTRAKT, '+     'O, H, L, C
From TBKURSZEILEN where FK_KONTRAKT = :fk order by FK_JDATUM asc'; 
IBQuery_oiEinKontrakt.ParamByName('fk').AsInteger:=fk1; 
IBQuery_oiEinKontrakt.Active:=true;   while not
IBQuery_oiEinKontrakt.EOF do begin       Chart_oi_Candles.AddXOHLC(  
     IBQuery_oiEinKontrakt.FieldByName('FK_JDATUM').AsDateTime,      
 IBQuery_oiEinKontrakt.FieldByName('O').AsFloat,       
 IBQuery_oiEinKontrakt.FieldByName('H').AsFloat,       
 IBQuery_oiEinKontrakt.FieldByName('L').AsFloat,       
 IBQuery_oiEinKontrakt.FieldByName('C').AsFloat         ); 
 IBQuery_oiEinKontrakt.Next;   end; end;                    


If you ask yourself, why I do it this way and not simpler:
Those SQL-series have different length. Where fk1 has data, fk3 has
none.
We do not know, which day exists for which foreign key.

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wp · 2022-09-30 15:32

I am attaching a test project showing that there is no bug in TAChart:
A lineseries and an ohlc series with common date values for x are
populated by random y values one after each other, but they are
displayed correctly on the same axis.

So, I don't know what's wrong in your case. The one thing that I
noticed is that you do not clear the Chart_oi_Candles series unlike
the others before adding the new data (but this would not append the
newly added data to the x axis).

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Nicole · 2022-09-30 16:22

"clear" was a very useful hint and I added it.
Nevertheless it did not cause the problem.

I am afraid, TAChart may have drawn., -  what I keyed in. Those query
may have reached too far into the past. So the problem is solved by
SQL in that way

select.... from... where ... datum > dat1