Calling R functions in Delphi
Anna Belova wrote:
Hellp Tom, Thank you so much! Several people have helped by pointing us to using R as a COM server. This is an exciting functionality, but unfortunately we are afraid we can't use it in this project. I really appreciate your thought and your time.
The solution I suggested was not using R as a COM server, but calling R directly in a thread. If you are using Delphi at all it should work. So, I consider the suggestion to be good. Besides, considering where your mail originates (a corporation), you might consider that I deserve a fee. Do you want a bank account number? Now, that might be difficult, considering that US bank systems are quite primitive by European standards, but nevertheless ... Tom
Regards, Anna ----------------------------------------- Anna Belova Abt Associates Inc. 4800 Montgomery Ln, St 600 Bethesda, MD-20814 phone: 301-347-5304 fax: 301-652-7530 http://www.abtassociates.com/environment Tom Backer Johnsen <backer at psych.uib To .no> Anna Belova <Anna_Belova at abtassoc.com> 12/05/2006 12:36 cc PM r-help at stat.math.ethz.ch Subject Re: [R] Calling R functions in Delphi Anna Belova wrote:
Hello All, We would like to call quantile() function from the R-package STATS in a Delphi program. If this is possible, could anyone provide us with an example?
It is possible, and in principle simple. The essentials: (1) Write a
file containing the something like a script in R with whatever
commands. (2) Start a process involving the execution of R with a
command line containing two arguments, the name of the command file
and the file where you want the output (results) to be. (3) wait for
the process to stop. So, here is a function (returns true if
everyhing worked OK) that does that:
function StartRAndWait (CommandLine : string) : Boolean;
var
Proc_info: TProcessInformation;
Startinfo: TStartupInfo;
ExitCode: longword;
CreateOK : Boolean;
begin
Result := False;
{ Initialize the structures }
FillChar(proc_info, sizeof (TProcessInformation), #0);
FillChar(startinfo, sizeof (TStartupInfo), #0);
Startinfo.cb := sizeof (TStartupInfo);
Startinfo.dwFlags := STARTF_USESHOWWINDOW or STARTF_USESTDHANDLES;
Startinfo.wShowWindow := SW_HIDE;
{ Attempt to create the process. If successful wait for it to end}
CreateOK := CreateProcess(Nil, PChar('R.exe ' + CommandLine), nil,
nil,False, CREATE_NEW_PROCESS_GROUP+NORMAL_PRIORITY_CLASS, nil,
nil, StartInfo, proc_info);
if (CreateOK) then begin
WaitForSingleObject (proc_info.hProcess, INFINITE);
GetExitCodeProcess(proc_info.hProcess, ExitCode);
Result := True
end;
CloseHandle(proc_info.hThread);
CloseHandle(proc_info.hProcess);
end;
The argument for the procedure (CommandLine) is a string, created by a
statement like:
Command := 'CMD BATCH ' + CommandFileName + ' ' + TempFileName;
where CommandFileName is the name of the file with the script, and
TempFileName is the name of the text file containing the output. The
procedure is fairly lowlevel, but it worked for me using Delphi 7. I
do not remember how I managed to put this together (probably a mix of
help from the R and Delphi lists), so please do not ask questions
about the finer details.
Tom
+----------------------------------------------------------------+
| Tom Backer Johnsen, Psychometrics Unit, Faculty of Psychology |
| University of Bergen, Christies gt. 12, N-5015 Bergen, NORWAY |
| Tel : +47-5558-9185 Fax : +47-5558-9879 |
| Email : backer at psych.uib.no URL : http://www.galton.uib.no/ |
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