v.reclass.pg
NAME
v.reclass.pg - Generate new vector map layer derived from
attribute data in the currently selected database. (GRASS-RDBMS Vector
Interface Program)
SYNOPSIS
v.reclass.pg
v.reclass.pg help
v.reclass.pg [-d] key=name
tab=name col=name
[where=name] input=name
[output=name]
type=name
ALTERNATE
v.reclass.pg [-sd] sql=name input=name
[output=name] type=name
DESCRIPTION
v.reclass.pg generates a new vector map layer based on the results
of one or more queries to the currently selected database. The user
constructs a series of mutually exclusive SQL retrieve statments designed to
return groups of records from the database. Each group of records should be
internally consistent in terms of attribute characteristics specified by
the user in the retrieve clause. These groups should also be mutually
exclusive, thereby insuring that a row returned by one retrieve clause is
not also returned by a subsequent retrieve clause. Each group of records
therefore forms the basis for a single category in the resulting GRASS
vector map. v.reclass.pg processes each retrieve statement in
order returning groups of records which will form a single category in the
resulting map. As each retrieve statement is processed the group of records
returned receives a common category value. The category value is
incremented by one for each subsequent retrieve statment which is processed.
The resulting reclass map will have one category for each of the original
retrieve statements.
For example, the rows associated with the first retrieve statement will be
assigned to category 1, those associated with the second retrieve statement
will be assigned to category 2 and so on. The output map will contain only
those line segments associated with database rows returned by the retrieve
statement(s).
COMMAND LINE OPTIONS
Flags:
- -d
- Disolve common boundaries between reclassed areas (default is no)
- -s
- Use [-s] for file SQL input.
Parameters:
- sql=filename
- Name of file containing SQL query statements
- key=databasecolumnname
- Key column in db
- tab=name
- Table containing [col]
- col=name
- Column to base reclass on
- where=name
- Where clause for query (ie. where col='paved')
- type=area/line/site
- Key column in db
- input=map
- Name of existing vector file to be reclassed using query output.
- output=map
- Name of new raster (reclass) file
EXAMPLE: produces vector map of primary and secondary roads.
v.reclass.pg sql=vect.sql key=tlid input=t.roads.pg output=t.roads.12
vect.sql:
retrieve unique (t.tlid,t.cfcc) from t in type1
where cfcc ~ "A1"
sort by tlid
retrieve unique (t.tlid,t.cfcc) from t in type1
where cfcc ~ "A2"
sort by tlid
BUGS
None known.
NOTE
This program requires the
Postgres modifications: Janne Soimasuo, Faculty of Forestry, University of
Joensuu, Finland.