Re: [GRASS-user] Check if a raster map has any valid pixel
Thank Glynn. But how can I retrieve min and max using a Python Script? 2010/10/25 Glynn Clements gl...@gclements.plus.com Kim Besson wrote: I have a python script where I need to check if an input raster map has any valid pixel (at least one pixel that is not null). How can I check this (easy and quick way?) in order to be integrated in my Script? Check the range: $ r.mapcalc --o 'foo = null()' $ r.info -r foo min=NULL max=NULL The range can only have min=max=NULL if there are no non-null cells. -- Glynn Clements gl...@gclements.plus.com ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] Check if a raster map has any valid pixel
Kim Besson wrote:
I have a python script where I need to check if an input raster map has
any
valid pixel (at least one pixel that is not null). How can I check this
(easy and quick way?) in order to be integrated in my Script?
Check the range:
$ r.mapcalc --o 'foo = null()'
$ r.info -r foo
min=NULL
max=NULL
The range can only have min=max=NULL if there are no non-null cells.
Thank Glynn. But how can I retrieve min and max using a Python Script?
import grass.script as grass
def isempty(map):
kv = grass.parse_command('r.info', flags = 'r', map = map)
return kv['min'] == 'NULL' and kv['max'] == 'NULL'
[CC'd to grass-dev]
You can't use grass.raster_info() as it tries to convert min and max
to floats, and raises ValueError on NULL.
r44049 fixes this, and returns None, but this should be considered
unstable. Arguably, it should be NaN, but AFAICT that would require
Python = 2.6, and I don't want to impose that requirement just for
this.
For now, r44049 at least suffices for the case where you don't care
about min/max (i.e. you can still get the bounds and resolution even
if the range is null). If you actually use min/max, r44049 just moves
the exception from the call to raster_info() to the point where you
try to perform arithmetic operations on None.
--
Glynn Clements gl...@gclements.plus.com
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[GRASS-user] Check if a raster map has any valid pixel
Greetings I have a python script where I need to check if an input raster map has any valid pixel (at least one pixel that is not null). How can I check this (easy and quick way?) in order to be integrated in my Script? Thjanks Kim ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Re: [GRASS-user] Check if a raster map has any valid pixel
Kim Besson wrote: I have a python script where I need to check if an input raster map has any valid pixel (at least one pixel that is not null). How can I check this (easy and quick way?) in order to be integrated in my Script? Check the range: $ r.mapcalc --o 'foo = null()' $ r.info -r foo min=NULL max=NULL The range can only have min=max=NULL if there are no non-null cells. -- Glynn Clements gl...@gclements.plus.com ___ grass-user mailing list grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
