st: by-group header in byable(onecall) programs

[Dirk Enzmann <dirk.enzmann@uni-hamburg.de>]

I'm struggling with programming a by-group header in a byable(onecall) 
program. Ideally it should match the header which is automatically 
created when using the -byable(recall)- option of -program-, i.e. using 
more than one by-variable it should be of the form

------------------------------------------------
-> var1 = label by-group var1, var2 = label by-group var2

Instead, so far I only managed to to create a header of the form

-----------------------------------------------
-> var1 var2 = label by-group var1 label by-group var2

Here is the version of a program which will create a header of the 
second type (what the program does not not the issue, I know that byable 
programs to center variables exist already):

* --- Begin Stata: -------------------------------

cap program drop foo

program foo, byable(onecall)
 version 12.1

 syntax varname(numeric) [if] [in], Generate(string)
 marksample touse
 tempvar bygr

 if "`_byvars'" == "" {
  sum `varlist' if `touse'
  qui gen `generate' = `varlist'-r(mean) if `touse'
 }
 else {
  qui egen `bygr' = group(`_byvars'), missing lname(bylab)
  qui levelsof `bygr' if `touse', local(K)
  qui gen `generate' = .
  foreach k of local K {
   di "{hline}" _n as res "-> `_byvars' = `: label (`bygr') `k''"
   sum `varlist' if `touse' & `bygr'==`k'
   qui replace `generate' = `varlist'-r(mean) if `touse' & `bygr'==`k'
   di
  }
 }
end

* --- End Stata. ---------------------------------

Are there any suggestions to create a header of the first type?

Dirk


========================================
Dr. Dirk Enzmann
Institute of Criminal Sciences
Dept. of Criminology
Rothenbaumchaussee 33
D-20148 Hamburg
Germany

phone: +49-(0)40-42838.7498 (office)
       +49-(0)40-42838.4591 (Mrs Billon)
fax:   +49-(0)40-42838.2344
email: dirk.enzmann@uni-hamburg.de
http://www2.jura.uni-hamburg.de/instkrim/kriminologie/Mitarbeiter/Enzmann/Enzmann.html
========================================
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