[GRASS-user] problem add-ons and python (windows7)

[Hamish]

Mattia wrote:
> I'm trying to solve my problem for a long time. I hope
> someone can help me. 
> I'm not expert but I really want to istall 2 add-on on grass
> 6.4.3RC3 on my win7. The add-ons are r.basin and r.ipso. I think
> there are problem with the python.exe and the PATHS. When I launch from
> console r.ipso I receive this error:
> 
> C:\Program Files (x86)\GRASS GIS
> 6.4.3RC3\extrabin\python.exe: can't open file 'r.ipso.py':
> [Errno 2] No such file or directory

the trouble with those two scripts are that they are written in python,
and GRASS 6 does not handle python addon scripts as well as it does
compiled C modules and UNIX shell scripts.

the bad news is as you experience they don't work out of the box right
now on Windows. The good news is that it is fixable. By moving and renaming
some of the files I could get them to run locally on Windows XP.
-- it's a solvable problem. I just ran r.basin.


gory technical details:
the basic one is Python.Make in GRASS 6's include/Make dir is not
currently set up to create the .bat file wrappers needed to launch
the scripts there. And/or the set PATHENV in \etc\Init.bat is not
working properly. (it knows about .py but doesn't know to associate
it with GRASS's python.exe)

Secondly, there is a .bat wrapper called %ADDONS%/scripts/r.basin.py.bat
which should be in %ADDONS%, and be named r.basin.bat. It contains a
single line, but that is wrong too, it should be set up for a python
script but it is created for a UNIX shell script. It should read like:

@"%GRASS_PYTHON%" "%GRASS_ADDON_PATH%/r.basin" %*

then the %ADDONS%\r.basin.py renamed to just r.basin, and finally
the batch file run as "r.basin.bat".  Then it works.


The better solution is to fix the .py association with python.exe, but
care is needed to pick the right one, and not hijack that setting for
the entire computer, since other software might be using another version
of python.


> I note that there are 2 python.exe. One in C:\Program Files
> (x86)\GRASS GIS 6.4.3RC3\extrabin\ and one in C:\Program Files
> (x86)\GRASS GIS 6.4.3 RC3\Pyton27\. I think that last one is the right
> and I think that probably there is an error with the PATH. It is
> possible?

do you really have a python.exe in your ...\GRASS GIS 6.4.3 RC3\Python27\
directory? For me it is only in ...\extrabin\ and in Python27\ there is
only support files.

As of last night's nightly build, 6.4.3svn explicitly expects to find
its python.exe in the \extrabin\ dir.

 
> Can anyone drive me to the solution? I would need to know
> where setting the different path beacuse I'm noob! I also see that
> there is a folder in C: User\AppData\Roaming\GRASS6\addons... It is
> normal that the add-ons are istalled ther instead of in GRASS GIS
> 6.4.3RC3 directory?

Yes, because the User can always write to their own AddData directly,
but on a multi-user or managed (corporate) system the user may not have
permission to change or add files to C:\Program Files.
There is a %GRASS_ADDON_PATH% variable set which says where your personal
scripts are stored. (can be set to multiple paths)
 
> When I launch r.basin I have an error that say aren't import
> sys, os and matplotlib. Even though I have istall matplotlib for
> Python27.

I don't get that error, just the one from g.parser that it can't get
the interface description (since it can't find the script). I'm surprised
that sys and os can't be found, that indicates that your %PYTHONPATH% is
broken since those two should always be built in. As for matplotlib I'm
not sure if GRASS ships that, it might not & so need to be installed
manually. (however you do that on Windows)


again, python + grass6 + MS Windows is a work in progress :)
fortunately only a few of the addons for grass6 are written in python,
so it's not a very widespread problem, but is certainly a pretty basic
need and something we want to support for the future.


Hamish