[R] Error when calling (R 4.0.x on Windows) from Python
Duncan Murdoch
murdoch@dunc@n @end|ng |rom gm@||@com
Wed Jan 27 22:25:08 CET 2021
On 27/01/2021 3:40 p.m., Bill Dunlap wrote:
> I believe the problem is from svn 77925 in gnuwin/front-ends/rcmdfn.c,
> which was committed a few days after 3.6.3 was released. Rterm used
> to put double quotes around a command line argument only if it
> contained a space, now it double quotes all arguments. It sees shell
> constructs like "1>" and the following file name as arguments and
> double quoting them hides them from the shell, leading to this
> problem. I think we may have to rely on the user supplying quotes as
> needed instead of blindly adding them.
Okay, now I see what you mean.
If you invoke R using R.exe, it asks cmd.exe to run Rterm.exe, so it is
possible that redirection would be handled.
If you invoke R directly using Rterm.exe, then my description down below
would be correct.
Duncan Murdoch
>
> -Bill
>
> On Wed, Jan 27, 2021 at 12:28 PM Duncan Murdoch
> <murdoch.duncan using gmail.com> wrote:
>>
>> On 27/01/2021 3:17 p.m., Duncan Murdoch wrote:
>>> On 27/01/2021 3:38 a.m., Martin Maechler wrote:
>>>>>>>>> Martin Maechler
>>>>>>>>> on Tue, 26 Jan 2021 12:37:58 +0100 writes:
>>>>
>>>>>>>>> Marcel Baumgartner
>>>>>>>>> on Tue, 26 Jan 2021 08:55:48 +0100 writes:
>>>>
>>>> >> Dear all, my colleague posted our issue on stackoverflow:
>>>>
>>>> >> Calling R script from Python does not save log file in
>>>> >> version 4 - Stack Overflow
>>>> >> [https://stackoverflow.com/questions/65887485/calling-r-script-from-python-does-not-save-log-file-in-version-4]
>>>>
>>>> >> It is about this kind of call to R:
>>>>
>>>> >> R.exe -f code.R --args "~/file.txt" 1> "~/log.txt" 2>&1".
>>>>
>>>> >> The issue is that the log.txt file is not created when
>>>> >> running R 4.x.x. The same code works perfectly fine with
>>>> >> R 3.6.x.
>>>>
>>>> >> Any idea what's going wrong as of version 4? Regards
>>>> >> Marcel
>>>>
>>>> > Dear Marcel, I think the solution is embarrassingly
>>>> > simple:
>>>>
>>>> >> From the SO post, where she showed a bit more detail than you
>>>> > show here, it's clear you have confused 'R.exe' and
>>>> > 'Rscript.exe' and what you say above is not true:
>>>>
>>>> > 'R.exe' was used for R 3.6.0 but for R 4.0.3, you/she used
>>>> > 'Rscript.exe' instead.
>>>>
>>>>
>>>> > ... as you've noticed now, they do behave differently,
>>>> > indeed!
>>>>
>>>> Well, this was not the solution to their -- Windows-only -- problem.
>>>> The problem *is* indeed visible if they only use R.exe (also
>>>> for R 4.0.3).
>>>>
>>>> I've commented more on the SO issue (see above),
>>>> notably asking for a *minimal* repr.ex. (reproducible example),
>>>> and one *not* using "<YOUR PATH>" and setwd() ..
>>>>
>>>
>>> Isn't this purely a Python or user problem? R shouldn't process
>>> redirection directives like
>>>
>>> 1> "~/log.txt" 2>&1
>>>
>>> because it's the shell's job to process those. If Python is acting as
>>> the shell, it needs to handle those things. If R was handling the
>>> command via
>>
>> Oops, sent before finishing:
>>
>> If R was handling the command via system() or system2(), it would handle
>> redirection itself. If it was using the Windows-only shell(), it would
>> call cmd.exe (by default) to handle redirection. (This is a difference
>> between R on Windows and R in Unix: in Unix a shell is always used.)
>>
>> Duncan Murdoch
>>
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