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v.reclass.1grass

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 output=name [type=string[,string,...]] [layer=integer] [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

output=name

Name for output vector map

type=string[,string,...]

Feature type
Options: point,line,boundary,centroid
Default: point,line,boundary,centroid

layer=integer

Layer number
A single vector map can be connected to multiple database tables. This number determines which table to use.
Default: 1

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.

SEE ALSO

v.dissolve, v.extract

GRASS SQL interface

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: 2008-11-11 05:16:34 +0100 (mar, 11 nov 2008) $

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