GRASS GIS manual: v.reclass

NAME

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

KEYWORDS

vector, reclass, attributes

SYNOPSIS

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

Flags:

--overwrite: Allow output files to overwrite existing files
--verbose: Verbose module output
--quiet: Quiet module output

Parameters:

input=name: Name of input vector map; Data source for direct OGR access
layer=string: Layer number or name; A single vector map can be connected to multiple database tables. This number determines which table to use. Layer name for direct OGR access.; Default: 1
type=string[,string,...]: Feature type; Options: point,line,boundary,centroid; Default: point,line,boundary,centroid
output=name: Name for output vector map
column=name: 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
rules=name: Full path to the reclass rule file

DESCRIPTION

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.

NOTES

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.

EXAMPLES

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
cat|I_vs_P
1|intermittent
2|perennial

BUGS

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

AUTHOR

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: 2010-09-15 13:39:49 -0700 (Wed, 15 Sep 2010) $

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