Note: A new GRASS GIS stable version has been released: GRASS GIS 7, available here. And see the new manual page here
v.reclass - Changes vector category values for an existing vector map according to results of SQL queries or a value in attribute table column.
vector, reclass, attributes
v.reclass input=name output=name [type=string[,string,...]] [layer=integer] [column=name] [rules=name] [--overwrite] [--verbose] [--quiet]
- Allow output files to overwrite existing files
- Verbose module output
- Quiet module output
- Name of input vector map
- Name for output vector map
- Feature type
- Options: point,line,boundary,centroid
- Default: point,line,boundary,centroid
- Layer number
- A single vector map can be connected to multiple database tables. This number determines which table to use.
- Default: 1
- The name of the column whose values are to be used as new categories
- The source for the new key column must be type integer or string
- Full path to the reclass rule file
v.reclass allows user to create a new vector map based on
the reclassification of an existing vector map. It also allows the user
to change the key column away from the default of "cat" with
the column option.
Rules file may contain on each row either pair:
(separated by space) or comment beginning with '#' (hash).
Definition of new category begins with keyword cat followed
by the new category value.
Keyword where specifies SQL where condition.
No table is created for the reclassed map if the column option is
used and the column type is integer (as the result could contain ambiguities).
If the column option is used and the column type is string, a new
table is created containing the newly generated cat numbers and a single
column containing the unique string column values, sorted in alphabetical
For dissolving common boundaries, see
Example 1: Reclass by rules
the rules file contains :
v.reclass input=land output=land_u type=boundary rules=land.rcl
Produces a new vector area map land_u containing boundaries from
land with area category values selected from database by SQL
# land reclass file
where use = 'E13' and owner = 'Jara Cimrman'
where use = 'E14'
select id from tland where use = 'E13' and owner = 'Jara Cimrman'
changed to category 1;
values selected from database by SQL select statement:
select id from tland where use = 'E14' changed to category 2.
Example 2: Reclass by attribute column
(North Carolina sample dataset)
v.reclass in=streams out=streams_by_type column=I_vs_P
No table is created for reclassed layer if rules option is used.
GRASS SQL interface
R.L. Glenn, USDA, SCS, NHQ-CGIS
from v.reclass to v.db.reclass and later to v.reclass in 5.7 rewritten
by Radim Blazek
Last changed: $Date: 2011-11-08 03:29:50 -0800 (Tue, 08 Nov 2011) $
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