[R] Rprintf not updating

[Sharpie]

Erik Wright wrote:
> 
> Hello all,
> 
> I am using Rprintf in a C for loop (from .Call) to print a progress
> indicator showing the current percent complete. The loop I am doing is an
> time intensive call to another function.  I have noticed that Rprintf does
> not print to the R-window until the entire loop has been completed.  When
> it reaches the end of the loop it suddenly prints 0 percent to 100 percent
> in a split second.  For less intensive function calls it prints properly
> while looping.  My question is this:  is there any way to force Rprintf to
> print to the screen during a loop?
> 
> On a related note, how can I show a percent sign in the output?  For
> example, Rprintf("0%"); only prints a zero.
> 
> Thanks!,
> Erik
> 

Perhaps you could use a callback to R's built in progress bar functions to
perform this for you in a nicely formatted way.  Something of the form:

  pBar <- txtProgressBar( min = , max = , type = 3 )
  
  cResults <- .Call( 'some_c_routine', some, args, including, pBar )

  close( pBar )

Since you pass the progress bar to the C routine, you could perform a
callback to the R function setTxtProgressBar() to update it every iteration. 
I posted an example of how to perform callbacks from C to R in this thread:

 
http://n4.nabble.com/Writing-own-simulation-function-in-C-td1580190.html#a1580423

Hope this helps!

-Charlie

-----
Charlie Sharpsteen
Undergraduate-- Environmental Resources Engineering
Humboldt State University
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