I am trying to use r.walk from python and the output file seems to be created correctly at the end of the python run.
However:
- while python is running I get the following error (but code keeps on running) : ERROR: Unable to create file <C:\A_GRID\PM\Grass\GrassDB/Location_L3/PERMANENT/.tmp/1824.0>
- All values of the output raster seem to be equal to 0.0 when I try to access them through a Grass garray. But I open the raster in Grass GUI all, I can see raster values were correctly populated for the whole raster. I get a nice cost surface.
Here is the core of my code : (coord is an array containing coordinates of point in the reference system of the current region)
a = garray\.array\(\)
grass\.run\_command\("g\.remove", rast=cost\_output\)
grass\.run\_command\("r\.walk", elevation="mnt\_l3\_toulouse@PERMANENT", friction="mnt\_l3\_toulouse@PERMANENT", output=cost\_output, coordinate=\[p1\[0\],p1\[1\]\],\_lambda=0\)
a\.read\(cost\_output\)
for p2 in coord:
x = int\(\(p2\[0\]\-w\)/ewres\)
y = int\(\(n\-p2\[1\]\)/nsres\)
print a\[y,x\]
I am trying to use r.walk from python and the output file seems to be
created correctly at the end of the python run.
However:
- while python is running I get the following error (but code keeps on
running) : ERROR: Unable to create file
<C:\A_GRID\PM\Grass\GrassDB/Location_L3/PERMANENT/.tmp/1824.0>
Just wild guessing: here is ^^^ a slash in the path-name. Is this valid in
Windows?
In fact the line of code that is causing the error is
a.read(cost_output) # a is a garray
At that moment it needs to create a temporary file but fails at building the correct path by putting slashes instead of back slashes (for windows) for his part. Isn't it a bug? Is there a possibility to give it the correct path?
ERROR: Unable to create file <C:\A_GRID\PM\Grass\GrassDB/Location_L3/PERMANENT/.tmp/29576.0>
Thank you,
Pierric
----- Mail original -----
De : Nikos Alexandris <nik@nikosalexandris.net>
À : grass-user@lists.osgeo.org; Pierric <pierric7@yahoo.com>
Cc :
Envoyé le : Mardi 2 juillet 2013 14h54
Objet : Re: [GRASS-user] r.walk output and garray
Pierric wrote:
Dear Grass community,
Salut Pierric
I am trying to use r.walk from python and the output file seems to be
created correctly at the end of the python run.
However:
- while python is running I get the following error (but code keeps on
running) : ERROR: Unable to create file
<C:\A_GRID\PM\Grass\GrassDB/Location_L3/PERMANENT/.tmp/1824.0>
Just wild guessing: here is ^^^ a slash in the path-name. Is this valid in
Windows?
- while python is running I get the following error (but code keeps on
running) : ERROR: Unable to create file
<C:\A_GRID\PM\Grass\GrassDB/Location_L3/PERMANENT/.tmp/1824.0>
Nikos:
Just wild guessing: here is ^^^ a slash in the path-name. Is this valid in
Windows?
Yeah I think it is valid in that context actually, even if it looks weird.
I'd check if the .tmp/ directory really exists and if you can create new files there by hand.
Hamish
ps- using PERMANENT as the day-to-day working mapset is not recommended.
