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opacs/histos/plots



	Hello

  I will answer your questions
 by piece.

  First, I shall explain how to do histograms
 and plot them with the XoPlot widget.

 HISTOGRAMS:
 ----------
  Histograms are handled by the Ho package.
 There is a running exemple in the HoT.exe
 program. If not done, reconstruct it with:

    UNIX> cd .../Ho/v1/mgr
    UNIX> source setup.csh
    UNIX> make
    UNIX> $HOBIN/HoT.exe

   Source is in HoT.c.

   The first way to create an Histogram object
 (OHist class) is by C programming.

  OHist hist1,hist2;
  ...
  /*one dimensionnal histogram.*/
  hist1 = OHistCreate ("my_histo",1,"x",10,0.,10.);
  
  /*two dimensionnal histogram.*/
  hist2 = OHistCreate ("my_histo_2",2,"x",10,0.,10.,
                                      "y",50,0.,20.);

  You fill an histo with OHistFill routine.

  for(count=0;count<1000;count++)
    {
      double            x,y;
      x                 = (double)rand();
      x                /= ((double)RAND_MAX);
      x                *= 10.;

      y                 = (double)rand();
      y                /= ((double)RAND_MAX);
      y                *= 20.;
      OHistFill         (hist1,x,1.);
      OHistFill         (hist2,x,y,1.);
    }

  Last argument is the weight of the entry.
  There are optimized routines to improve the filling.
  For 1D:
      OHistFillFastOne  (hist,x,1.);
  For 2D:
      OHistFillFastTwo  (hist,x,y,1.);


  Deletion of an histogram is done with 
 the OHistDelete routine:

   OHistDelete (hist1);

  Look the OHist.h, and OHist.c for other
 convenient routines that work on an OHist object.


 PLOTTING:
 ---------
  Plotting is done with the XoPlot widget.
 You have to create one in you interface. The
 best is to create one in the odb file.
  The "user.odb" template contains the "user_plot"
 XoPlot widget.
  Mainly the link between the XoPlot widget and
 an OHist object is done through the setting of the
 resource "toPlot".
  The setting of the resource produces a "representation"
 of the histogram by the plot widget. This involves that the
 histogram must be created and filled  when you set
 the resource. 
  NOTE that the XoPlot widget DO NOT SURVEY
 the state of the histogram.
  Then if you fill again, or change booking parameters 
 of the the histo, you have to trigger a new 
 representation of it in the plot
 with a new setting of the "toPlot" resource.

  Maily what you should do in your display:
  - create some histo at startup.
  - clear, fill, plot them at each event
  
  You can create an osh command "histo" that 
 look like this:

  ...
  OShAddCmd ((OSh)a_osh,OCmdCreate("KLOE/histos",(VoidProc)histos));
  ....
  /*create histos*/
  OHistCreate("KLOE_ecal_energy",....)
  ....
  WoStartup ();
  .....


/***************************************************************************/
static int histos (
 int    a_argn
,char** a_args
,OExec  a_exec
)
/***************************************************************************/
/*
*/
/*!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!*/
{
  OHist hist_ecal_energy;
  Widget plot;
/*.........................................................................*/
  if( (a_argn!=1) && (a_argn!=2) ){CWarnF ("%s: bad arg number.\n",a_args[0]);return EXIT_FAILURE;}

  hist_ecal_energy = OHistFrName ("KLOE_ecal_energy");
  
  OHistRaz (hist_ecal_energy);

  for(...)
    {
      double energy;
      /*Get ecal data.*/
      energy = ....
      OHistFill (hist_ecal_energy,energy,1.);
    }


  /*We trigger a representation of the histo 
    in the user_plot widget.*/  
 
  plot = OWidgetFrName ("user_plot");
/*Reset objects to plot.*/
  OWidgetSetResource (plot,"toPlot","",False); 
/*Plot the KLOE_ecal_energy histogram*/
  OWidgetSetResource (plot,"toPlot","KLOE_ecal_energy",False); 

  OExecPutPipe (a_exec,0);

  return EXIT_SUCCESS;
}
  
   


  When this is done, you execute the "histos" 
 command in any buildSceneCallback. For exemple
 on the user_plot widget:

   user_plot.buildSceneCallback = osh> histos


  This is the basic mechanism. 



  The OHist class is declared to the type 
 manager. Then you could see histos with:
    osh> collect OHist | dump
 or
    osh> collect OHist where name eq KLOE_ecal* | dump
  In principle you can declare histo in an odb
 file (today only 1D !!!):
    hist.odb
     begin OHist
       name = KLOE_ecal_energy
       dimension = 1
       title = hello
       xn = 100
       xmin = 0.
       xmax = 10.
     end
  you load the file with the command:
    osh> load hist.odb
  The load command will do the OHistCreate.
  Look HoT.c for a running example.


  Next version will have the "create" and
 "fill" command that will permits to 
 create histo and fill them with 
 object properties declared to the "type manager".
 Them mainly all histos manipulation
 wil be done without user C programming.

  I shall put in the GEANT template
 that come with "Wo" full exemples of all these.



         G.Barrand