v.reclass.1grass - Man Page

Changes vector category values for an existing vector map according to results of SQL queries or a value in attribute table column.


vector, reclassification, attributes


v.reclass --help
v.reclass input=name  [layer=string]   [type=string[,string,...]]  output=name  [column=name]   [rules=name]   [--overwrite]  [--help]  [--verbose]  [--quiet]  [--ui]



Allow output files to overwrite existing files


Print usage summary


Verbose module output


Quiet module output


Force launching GUI dialog


input=name [required]

Name of input vector map
Or data source for direct OGR access


Layer number or name
Vector features can have category values in different layers. This number determines which layer to use. When used with direct OGR access this is the layer name.
Default: 1


Input feature type
Options: point, line, boundary, centroid
Default: point,line,boundary,centroid

output=name [required]

Name for output vector map


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:

keyword value

(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 order.

For dissolving common boundaries, see v.dissolve.

Either the rules or column option must be specified.


Example 1: Reclass by rules

v.reclass input=land output=land_u type=boundary rules=land.rcl

The rules file contains:

# land reclass file
cat 1
where use = ’E13’ and owner = ’Jara Cimrman’
cat 2
where use = ’E14’

Produces a new vector area map land_u containing boundaries from land with area category values selected from database by SQL select statement:
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
v.db.select streams_by_type

Known Issues

No table is created for reclassed layer if the rules option is used.

See Also

v.dissolve, v.extract

GRASS SQL interface


from v.reclass to v.db.reclass and later to v.reclass in 5.7 rewritten by Radim Blazek

Source Code

Available at: v.reclass source code (history)

Accessed: Tuesday Mar 19 11:02:19 2024

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