Steven Stoddard wrote:
I am currently in the process of learning grass and trying to assemble a database to work off of for my research. I am importing many files and trying to get them into a raster format that is amenable to analysis--floating point or integer maps. I have maps though that were imported from .e00 that are in raster format, but are categorized sequentially (e.g. 1-120) and their labels are a floating point value. How do I get rid of the category number and instead have only the fp value so I can do manipulations with mapcalc etc?
Just for background, the imported map was first in vector format and all polygons were assigned a unique id with a floating point value as the attribute. I reclassified this map so that the categories at least corresponded to same floating point values and were sorted in increasing fashion.
You can use r.reclass the same way as v.reclass on the file imported with
m.in.e00 : just transform the cat file in soething usable as input for
r.reclass. What I don't know is how to force the resulting file to be
a floating value raster... Maybe it is easier to start from the vector
file and use v.to.rast (with the appropriate dig_cats file) to produce
the raster file...
Here follows a copy a message I posted some days ago :
As a reminder : If there is only one attribute (other than the standard ESRI
attributes for lines or areas), ther is only one dig_cats file created, and
its name is like the dig file name. If there is many attributes, there is
as many dig_cats files, named <vector_file_name>.<attribute_name>. In this case
the first thing to do is to go in the dig_cats directory and set a symbolic
link to the dig_cats file you want as the new dig_att values.
After that, you need only a two line command to change the att values. The
best is to take an example :
dig file name is brucom,
dig_att/brucom looks like :
# 48 categories
brucom
0.00 0.00 0.00 0.00
1:67482
2:67492
3:67354
4:67240
etc.
What you have to type :
export LOCATION=<your mpaset location>
sed -e '1,4d' -e 's/
= /' $LOCATION/dig_cats/brucom | v.reclass input=brucom output=brucom1 type=area
v.support brucom1
The first line was added since $LOCATION is no longer set at grass startup...
The second one do the job : sed convert the dig_att file in a form usable by
v.reclass. You have to change
- the file names and the location (obviously)
- the type=area in type=line if you have lines instead of areas
The third line is mandatory for some other programs to work (v.digit, d.what.vect,
etc.)
--
Michel Wurtz - Auzeville-Tolosane