Ciao Ivan,
On Wed, Jun 26, 2013 at 5:40 AM, Ivan Marchesini
<ivan.marchesini@gmail.com> wrote:
I have this small code:
grass.run_command("v.to.rast", input=ocs, type="line", output="tmp_ocs", use="val", overwrite=True)
grass.mapcalc("$outmap = $a", a = dtm, outmap="demcut", overwrite = true)
grass.run_command("g.remove", rast="visitati")
np_ocs = raster.RasterNumpy("tmp_ocs")
np_ocs.open()
visited=np_ocs*0
visited.open()
for i in range(1,new.shape[0]-1):
for j in range(1,new.shape[1]-1):
if np_ocs[i,j] == 1:
visited[i,j] = 1
else:
visited[i,j] = 3
visited.name='visitati'
visited.close()
sys.exit("stop")
Some note on the code:
1) maybe to this kind of things you should consider to use the
r.mapcalc instead of pygrass;
2) Why are you using RasterNumpy?
- RasterNumpy is quite slow because need to export your map on the
hard disk, load in memory using numpy.memmap... therefore, if
possible, try to avoid this class...
- Avoid to use cycle in python, they are really slow and are
working only with small region.
Following the first point the cycle will be:
{{{
from grass import script as grass
grass.run_command("r.mapcalc", expression="{outmap} = if({a}==1, 1,
3)".format(a = "tmp_ocs", outmap="visited"), overwrite = True)
}}}
About the second point:
{{{
from grass.pygrass.raster import RasterRow
with RasterRow("tmp_ocs") as ocs:
new = RasterRow("visited")
new.open("w", "CELL")
for row in ocs:
rbool = (row == 1)
row[rbool] = 1
row[~rbool] = 3
new.write(row)
new.close()
}}}
In this way only the cycle on the rows is done in python, all the
other cycle are done in C trough numpy.
But to do something so simple I suggest to use r.mapcalc.
When I run it I obtain a lot of:
WARNING: rast=visitati,visitati: files could be the same, no rename
possible
I cannot understand where the warnings arise... and why..
I think the warning raise, here:
{{{
visited.name='visitati'
}}}
In this piece of code you are assign a new name to the raster, but the
map already exist...
Therefore as Luca said, should be sufficient to add:
{{{
visited.overwrite = True
visited.name = 'visitati'
}}}
let us know.
Pietro
