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Debug with set.seed()

2 messages · Tong Wang, Patrick Burns

Original
Tong Wang
# 
HI, all
    I am debugging an R code with dynamically loaded function in it.  It seems set.seed(n) does not give me the same 
random draws every time.  Could somebody tell me what I should do to get the same outcome verytime ?
    I am not sure what infomation is relevent to this question , the following is a really scatchy description of the code I wrote.I am using the R-2.4.1 built under Cygwin. OS is WinXP.

Thanks a lot  for any help.  
  
    Myfunction<-function(...) {
        .......
        drawsomething<-function(){  out<- .C( "drawit"...........)  
                                                             var <<- out$var  # assign the outputs}
        .......
        for( i in 1 : iter) { .........
                                    drawsomething()
                                    .......... }

       reture( var.stor )     #return stored result
}
Patrick Burns
# 
I think you will find that 'set.seed' does give you the same
random state each time.  That you don't get the same result
each time implies a bug in your code.  Looking for uninitialized
variables would probably be a good start.  Using valgrind
under Linux would most likely find the error quickly.

Also, using '<<-' is generally a bad idea.

Patrick Burns
patrick at burns-stat.com
+44 (0)20 8525 0696
http://www.burns-stat.com
(home of S Poetry and "A Guide for the Unwilling S User")
Tong Wang wrote: