R help - May 2003 - several regression lines in panel of xyplot (trellis graphics)

Dear r-help,

  I need to draw xyplot() graphs with several regression lines:
  one line for the whole range of x (the variable on the horizontal
  axis) and two additional lines for subranges of x.
  
  Is it possible to make first regression line (panel.lmline(x,y,...);)
  to be drawn on the whole graph
  and regression lines of the subsets to be drawn only over their subsets?

  I have defined
plot.panel=function(x,y,...){
  panel.xyplot(x,y,...);
  panel.lmline(x,y,...);
  panel.lmline(x[1:9],y[1:9],...);
  panel.lmline(x[10:23],y[10:23],...);
  panel.grid(h=-1,v=-1,...);
};

then I draw plots:
  xyplot(<blah-blah-blah>,panel=plot.panel,<...>)

  This command draws graphics, but all regression lines on them are
  drawn from the left side to the right side, i.e. over the whole x
  range...

-- 
Best regards
Wladimir Eremeev                                     mailto:wl at eimb.ru

=========================================================================Research
Scientist                                Leninsky Prospect 33,
Space Monitoring & Ecoinformation Systems Sector, Moscow, Russia, 119071,
Institute of Ecology,                             Phone: (095) 135-9972;
Russian Academy of Sciences                       Fax: (095) 954-5534

Wladimir Eremeev <wl at eimb.ru> writes:
> Dear r-help,
> 
>   I need to draw xyplot() graphs with several regression lines:
>   one line for the whole range of x (the variable on the horizontal
>   axis) and two additional lines for subranges of x.
>   
>   Is it possible to make first regression line (panel.lmline(x,y,...);)
>   to be drawn on the whole graph
>   and regression lines of the subsets to be drawn only over their subsets?
> 
>   I have defined
> plot.panel=function(x,y,...){
>   panel.xyplot(x,y,...);
>   panel.lmline(x,y,...);
>   panel.lmline(x[1:9],y[1:9],...);
>   panel.lmline(x[10:23],y[10:23],...);
>   panel.grid(h=-1,v=-1,...);
> };
> 
> then I draw plots:
>   xyplot(<blah-blah-blah>,panel=plot.panel,<...>)
> 
>   This command draws graphics, but all regression lines on them are
>   drawn from the left side to the right side, i.e. over the whole x
>   range...
I think you will need to do the linear model fits to the data subsets
within the panel function then use panel.segments to add the lines.