[R] How to defeat buffering in Rgui?

[Spencer Graves]

duh, of course:  Thanks very much. Spencer


On 6/29/2012 11:44 AM, jim holtman wrote:
> One of the things that you should learn is how to profile (Rprof) your
> code to see where time is being spent.  If you did, you would have
> seen that all the time is being spent in 'flush.console'.  As was
> pointed out in a previous response, only call it when something is
> printed.
>
>    0  31.1 root
>    1.   31.1 flush.console
>    1.    0.0 %%
>    1.    0.0 sin
>    1.    0.0 cat
>
> If you modify your code:
>
> for(i in 1:1e4){
>     tst <- sin(i)
>     if((i%%1e2)==0)cat(i, "")
>     if((i%%1e3)==0){cat('\n'); flush.console()}
>     # flush.console()
> }
>
>
> You will notice a very large speedup.
>
>    0   0.5 root
>    1.    0.4 flush.console
>    1.    0.0 cat
>    1.    0.0 ==
>
>
>
>
> On Fri, Jun 29, 2012 at 1:15 PM, Spencer Graves
> <spencer.graves at structuremonitoring.com> wrote:
>> 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
>>>
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