[R] How to defeat buffering in Rgui?

[Spencer Graves]

Dear Prof. Ripley:


       Thanks for the reply.  Unfortunately, flush.console() seems to 
lock up my system.  I tried the following:


for(i in 1:1e7){
     tst <- sin(i)
     if((i%%1e5)==0)cat(i, "")
     if((i%%1e6)==0)cat('\n')
     flush.console()
}


       This slows down Rgui 2.15.1 (32-bit) by a factor of roughly 350:  
In Rterm (64-bit), on my dual core 64-bit Windows 7 system, this ran to 
completion in 1 minute;  this same code without flush.console() ran to 
completion in 35 seconds in Rgui 2.15.1 (64-bit), then presented the 
display.  Watching it run in Rgui, it seemed to consume roughly half of 
one CPU while making very slow progress.  I started timing it when it 
displayed 200000;  24 minutes later, I noticed it was displaying 
900000.  That produces an estimate of 340 minutes to complete.


       I'd like to use this to give users (e.g., of a CRAN package) a 
progress report on long computations:  Otherwise, a user doesn't know if 
the computation will every complete.


       Suggestions?


       Thanks,
       Spencer


On 6/29/2012 12:12 AM, Prof Brian Ripley wrote:
> See the posting guide: this is in the FAQ which you are expected to 
> consult before posting. See
>
> http://cran.r-project.org/bin/windows/base/rw-FAQ.html#The-output-to-the-console-seems-to-be-delayed 
>
>
> and ?flush.console .
>
> On 29/06/2012 08:01, Spencer Graves wrote:
>> Hello, All:
>>
>>
>>        Does anyone know how to defeat buffering of output to the console
>> from Rgui?  I routinely print progress reports to the console from
>> within Rterm running under Emacs with ESS (Emacs Speaks Statistics); see
>> the example below.  However, when I run the same example under Rgui, it
>> queues all the output until the computations are complete.
>>
>>
>>        How can I monitor the progress of computations in both Rgui and
>> Rterm?
>>
>>
>>        Consider the following:
>>
>>
>> for(i in 1:1e7){
>>      tst <- sin(i)
>>      if((i%%1e5)==0)cat(i, "")
>>      if((i%%1e6)==0)cat('\n')
>> }
>>
>>
>>        For Rterm 2.15.1 running under Emacs with ESS (Emacs Speaks
>> Statistics), this prints 10000, then pauses before printing 200000,
>> etc., until it gets to 1000000, printing 10 numbers in each row.
>>
>>
>>        However, in Rgui 2.15.1, it queues all the numbers and prints
>> them all together when it completes the computation.  The following is
>> similar:
>>
>>
>> for(i in 1:1e7){
>>      tst <- sin(i)
>>      if((i%%1e5)==0)print(i)
>>      if((i%%1e6)==0)cat('\n')
>> }
>>
>>
>>> sessionInfo()
>> R version 2.15.1 (2012-06-22)
>> Platform: i386-pc-mingw32/i386 (32-bit)
>>
>> locale:
>> [1] LC_COLLATE=English_United States.1252
>> [2] LC_CTYPE=English_United States.1252
>> [3] LC_MONETARY=English_United States.1252
>> [4] LC_NUMERIC=C
>> [5] LC_TIME=English_United States.1252
>>
>> attached base packages:
>> [1] stats     graphics  grDevices utils     datasets  methods base
>>
>>
>>        Thanks,
>>        Spencer
>