I am a GRASS newbie, so I apologise in advance for the simplicity of
my question. I have a set of sites and I would like to create a series
of circular buffers around each site and then use r.stats to extract
some information from each buffer in combination with a land cover
map. My problem is that if I simply use the v.to.rast and r.buffer
commands to obtain the buffers, many of these will clash into each
other because the sites are too close. I was wondering whether there
is any script out there capable of creating buffers one at the time
starting from a set of sites and then using the r.stats command to
extract info from data layer. If not, I would be really happy if you
could point me in the right direction! I have found some code (see
below) that has proved useful, but does not do exactly what I want.
Basically, by starting from a set coordinates, the script is capable
of zooming into a region around each site and extracting the relevant
information using the r.stats command. Unfortunately I have no clue on
how to create the individual buffers. Any help would be appreciated!
thanks!
Alessandro
#!/bin/sh
#replace 'foo' with name of input file (easting and northing) #replace 'outfile' with name of output file #replace 'LCM2000a' with the name of the map from where you want to
extract some information
numSites=`wc -l foo | awk '{print $1}'`
winSize=500
for (( site=1 ; site <= $numSites ; site++ ));
do
cent_e=`awk '{if(NR=='$site') printf("%.0f", $1)}' foo`
cent_n=`awk '{if(NR=='$site') printf("%.0f", $2)}' foo`
On Tue, 2009-10-27 at 23:24 +0100, Alessandro Bertan wrote:
Dear GRASS users,
I am a GRASS newbie, so I apologise in advance for the simplicity of
my question. I have a set of sites and I would like to create a series
of circular buffers around each site and then use r.stats to extract
some information from each buffer in combination with a land cover
map. My problem is that if I simply use the v.to.rast and r.buffer
commands to obtain the buffers, many of these will clash into each
other because the sites are too close. I was wondering whether there
is any script out there capable of creating buffers one at the time
starting from a set of sites and then using the r.stats command to
extract info from data layer. If not, I would be really happy if you
could point me in the right direction!
Just an (untested) idea: why not create all buffers as separate, unique
raster (with r.buffer) or vector (with v.buffer) maps and loop over
them? Are the sites _too_ many?
I have found some code (see
below) that has proved useful, but does not do exactly what I want.
I think the code below will give stats based on the queried map _and_
only within the defined geographic region (g.region -p).
Better to use r.statistics, for example the command (within the loop
over the sites) could look like:
r.statistics base=BUFFER cover=LANDCOVER method=diversity
Basically, by starting from a set coordinates, the script is capable
of zooming into a region around each site and extracting the relevant
information using the r.stats command. Unfortunately I have no clue on
how to create the individual buffers. Any help would be appreciated!
thanks!
Alessandro
Best regards, Nikos
--%<--
#!/bin/sh
#replace 'foo' with name of input file (easting and northing) #replace 'outfile' with name of output file #replace 'LCM2000a' with the name of the map from where you want to
extract some information
numSites=`wc -l foo | awk '{print $1}'`
winSize=500
for (( site=1 ; site <= $numSites ; site++ ));
do
cent_e=`awk '{if(NR=='$site') printf("%.0f", $1)}' foo`
cent_n=`awk '{if(NR=='$site') printf("%.0f", $2)}' foo`
??v.sample.buffer?? addon
and fast stats using 3rd party program called starspan (??)
Alessandro:
I am a GRASS newbie, so I apologise in advance for the
simplicity of
my question. I have a set of sites and I would like to
create a series
of circular buffers around each site and then use r.stats
to extract
some information from each buffer in combination with a
land cover
map. My problem is that if I simply use the v.to.rast and
r.buffer
commands to obtain the buffers, many of these will clash
into each
other because the sites are too close. I was wondering
whether there
is any script out there capable of creating buffers one at
the time
starting from a set of sites and then using the r.stats
command to
extract info from data layer. If not, I would be really
happy if you
could point me in the right direction! I have found some
code (see
below) that has proved useful, but does not do exactly what
I want.
Basically, by starting from a set coordinates, the script
is capable
of zooming into a region around each site and extracting
the relevant
information using the r.stats command. Unfortunately I have
no clue on
how to create the individual buffers. Any help would be
appreciated!
thanks!
Alessandro
#!/bin/sh
#replace 'foo' with name of input file (easting and
northing) #replace 'outfile' with name of output file #replace 'LCM2000a' with the name of the map from where you
want to
extract some information
numSites=`wc -l foo | awk '{print $1}'`
winSize=500
for (( site=1 ; site <= $numSites ; site++ ));
do
cent_e=`awk '{if(NR=='$site') printf("%.0f", $1)}' foo`
cent_n=`awk '{if(NR=='$site') printf("%.0f", $2)}' foo`
Thank you for your useful indications! It seems that the addon
v.what.rast.buffer is capable of doing what I want. I am trying to
modify it by substituting r.univar -g with r.stats -anl but I get the
following error message:
Calculating stats for cat ...
Sorry, <map> is not a valid parameter
ERROR: Required parameter <input> not set:
(Name of input raster map(s)).
I would greatly appreciate if you give me some suggestions on how me
to solve this problem!
Hello everybody,
I'd like to know how to do with such projections:
Lambert III
United Kingdom
L-EST'92
CS_KKJ24North
They are not available in the list at the creation of a new location.
Thanks
Stéphanie
# OSGB 1936 / British National Grid
<27700> +proj=tmerc +lat_0=49 +lon_0=-2 +k=0.9996012717 +x_0=400000 +y_0=-100000 +ellps=airy +datum=OSGB36 +units=m +no_defs <>
The EPSG code is 27700. Beware that old versions of proj (prior to October 2007) don't have the OSGB36 datum and will plot your data offset by up to 100 m.
Later
John
--
Dr John Stevenson
Postdoctoral Research Associate
School of Earth, Atmospheric and Environmental Sciences
Williamson Building (Room 2.42)
University of Manchester
Manchester M13 9PL, UK
tel. +44(0)161 306 6585; fax. +44(0)161 306 9361;
john.stevenson@manchester.ac.uk
Did you look at spatial http://www.spatialreference.org/ for the EPSG code, which you can then add to the list with the corresponding parameters...
Best regards
Alex
FAROUX STEPHANIE a écrit :
Hello everybody,
I'd like to know how to do with such projections:
Lambert III
United Kingdom
L-EST'92
CS_KKJ24North
They are not available in the list at the creation of a new location.
Thanks
Stéphanie
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__________ Information from ESET Mail Security, version of virus signature database 4552 (20091028) __________
If nothing matches your needs, you'll have to create locations by
yourself, which requires to know geodetic definition for each.
Yours,
Vincent.
Le mercredi 28 octobre 2009 à 16:31 +0100, FAROUX STEPHANIE a écrit :
Hello everybody,
I'd like to know how to do with such projections:
Lambert III
United Kingdom
L-EST'92
CS_KKJ24North
They are not available in the list at the creation of a new location.
Thanks
Stéphanie
_______________________________________________
grass-user mailing list
grass-user@lists.osgeo.org http://lists.osgeo.org/mailman/listinfo/grass-user
Thank you for your useful indications! It seems that the addon
v.what.rast.buffer is capable of doing what I want. I am trying to
modify it by substituting r.univar -g with r.stats -anl but I get the
following error message:
Calculating stats for cat ...
Sorry, <map> is not a valid parameter
ERROR: Required parameter <input> not set:
(Name of input raster map(s)).
I would greatly appreciate if you give me some suggestions on how me
to solve this problem!
thanks again!
Alessandro
Alessandro,
Some mounth ago I have modified the script to have a report for each point into a text file. Here the code:
#%option
#% key: prefix_stats
#% type: string
#% gisprompt: new_file,file,output
#% key_desc: name
#% description: Name for output prefix stats data (if omitted or "-" output to stdout)
#% required: no
#%end
[...]
PREFIX_STATS="$GIS_OPT_PREFIX_STATS"
[...]
if [ -e "$PREFIX_STATS" ] ; then
g.message -e "Output File [$PREFIX_STATS] already exists"
exit 1
fi