Q: How can I copy values from one Series to another ?

One solution is to make the second Series DataSource to be the first Series:

DELPHI CODE : 

 Series2.DataSource := Series1 ;

CBUILDER CODE : 

 Series2->DataSource=Series1;

Another solution is to call the AssignValues method:

DELPHI CODE : 

 Series2.AssignValues( Series1 );

CBUILDER CODE : 

 Series2->AssignValues(Series1);

Q: How can I display the sum of all the values in a Chart Series?

DELPHI CODE : 

 ShowMessage( FloatToStr( Series1.YValues.Total ) );

CBUILDER CODE : 

 ShowMessage(FloatToStr(Series1->YValues->Total));

Q: How can I group and plot values by month or by week ?

Q: How to add NULL values to a chart ?

DELPHI CODE : 

 Series1.AddNull( '' );
 Series1.AddNullXY(2,3,'');

CBUILDER CODE : 

 Series1->AddNull("");
 Series1->AddNullXY(2,3,"");

Q: How to remove gaps after deleting points in a Series ?

DELPHI CODE : 

Series1.Delete( 3 );
Series1.XValues.FillSequence;

CBUILDER CODE : 

 Series1->Delete(3);
 Series1->XValues->FillSequence();

Q: Is there a way to specify a range of points to be shown on chart? For example, if we add 50 points to a Series, have the chart show points 34 to 41 only.

The Series OnBeforeAdd event can be used to limit which points do we actually add (see the code bellow):

DELPHI CODE : 

var tmpCount:integer;

procedure TForm1.FormCreate(Sender: TObject);
begin
  Series1.Clear;  //force clear, just in case
  Series1.FillSampleValues(50);
end;

function TForm1.Series1BeforeAdd(Sender: TChartSeries): Boolean;
begin
  Inc(tmpCount);
  result:= (tmpCount>34) and (tmpCount<41); //add only desired values
end;

procedure TForm1.Series1ClearValues(Sender: TChartSeries);
begin
  tmpCount:=0; //reset counter
end;

CBUILDER CODE : 

TForm1 *Form1;
int tmpCount;
//---------------------------------------------------------------------------
__fastcall TForm1::TForm1(TComponent* Owner)
        : TForm(Owner)
{
}
//---------------------------------------------------------------------------

void __fastcall TForm1::FormCreate(TObject *Sender)
{
        Series1->Clear();  //force clear, just in case
        Series1->FillSampleValues(50);

}
//---------------------------------------------------------------------------

void __fastcall TForm1::Series1ClearValues(TChartSeries *Sender)
{
        tmpCount=0; // reset counter
}
//---------------------------------------------------------------------------
bool __fastcall TForm1::Series1BeforeAdd(TChartSeries *Sender)
{
  tmpCount++;
  bool result= (tmpCount>34) && (tmpCount<41); //add only desired values
  return result;
}
//---------------------------------------------------------------------------

Q: I'd like to connect points in "chornological" order i.e. the way I add them. But TeeChart seems to connect points by ascending XValues.

Well, the Series.XValues.Order:=loAscending; is the default setting for connecting points by line. If you require something else, you can easily change the "line drawing" order by:

DELPHI CODE : 

  Series.XValues.Order:=loNone;

CBUILDER CODE : 

 Series1->XValues->Order=loNone;

Q: If I use a Series, then the Null values are always displayed as 0. How can I avoid this?

The AddNull (or the AddNullXY in TeeChart4) method is actually only the standard Add (or AddXY in TeeChart4) method with the Color=clNone; I took this out of the source code:

Function TChartSeries.AddNull(Const ALabel:String):Longint;
begin
result:=Add( 0, ALabel, clNone );
end;

Function TChartSeries.AddNullXY(Const X,Y:Double; Const ALabel:String):Longint;
begin
result:=AddXY(X,Y,ALabel,clNone );
end;

The solution:

a) if you know the range in advance, use the AddNullXY(x,y,'') to add Null points, where y is in [min,max] interval.

b) if you don't know the y-range in advance, utilize the Series OnAfterAdd event to "shift" null values up or down, depending if they are min or max values (see the code bellow):

DELPHI CODE : 

procedure TForm1.Series1AfterAdd(Sender: TChartSeries;
ValueIndex: Integer);
var i:integer;
begin
for i:=Sender.FirstValueIndex to Sender.LastValueIndex do
 if Sender.IsNull(ValueIndex) then
   if Sender.YValue[ValueIndex]=Sender.YValues.MinValue then
    Sender.YValue[ValueIndex]:=Sender.YValues.MaxValue
  else
  if Sender.YValue[ValueIndex]=Sender.YValues.MaxValue then
   Sender.YValue[ValueIndex]:=Sender.YValues.MinValue
end;

CBUILDER CODE : 

void __fastcall TForm1::Series1AfterAdd(TChartSeries *Sender,
      int ValueIndex)
{
   for (int i=Sender->FirstValueIndex;i<=Sender->LastValueIndex;i++)
   {
    if (Sender->IsNull(ValueIndex))
     if (Sender->YValues->Value[ValueIndex]==Sender->YValues->MinValue)
       Sender->YValues->Value[ValueIndex]=Sender->YValues->MaxValue;
     else
        if (Sender->YValues->Value[ValueIndex]==Sender->YValues->MaxValue)
          Sender->YValues->Value[ValueIndex]=Sender->YValues->MinValue;
   }
}