python::vector Namespace Reference

Functions
def	vector_db
	Return the database connection details for a vector map (interface to `v.db.connect -g').
def	vector_layer_db
	Return the database connection details for a vector map layer.
def	vector_columns
	Return a dictionary (or a list) of the columns for the database table connected to a vector map (interface to `v.info -c').
def	vector_history
	Set the command history for a vector map to the command used to invoke the script (interface to `v.support').
def	vector_info_topo
	Return information about a vector map (interface to `v.info -t').
def	vector_db_select
	Get attribute data of selected vector map layer.
def	vector_what
	Query vector map at given locations.

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Function Documentation

def python::vector::vector_columns	(		map,
			layer = None,
			getDict = True,
			args
	)

Return a dictionary (or a list) of the columns for the database table connected to a vector map (interface to `v.info -c').

>>> vector_columns(urbanarea, getDict = True)
{'UA_TYPE': {'index': 4, 'type': 'CHARACTER'}, 'UA': {'index': 2, 'type': 'CHARACTER'}, 'NAME': {'index': 3, 'type': 'CHARACTER'}, 'OBJECTID': {'index': 1, 'type': 'INTEGER'}, 'cat': {'index': 0, 'type': 'INTEGER'}}

>>> vector_columns(urbanarea, getDict = False)
['cat', 'OBJECTID', 'UA', 'NAME', 'UA_TYPE']

Parameters:

map	map name
layer	layer number or name (None for all layers)
getDict	True to return dictionary of columns otherwise list of column names is returned
args	(v.info's arguments)

Returns:

dictionary/list of columns

Definition at line 97 of file lib/python/vector.py.

def python::vector::vector_db	(		map,
			args
	)

Return the database connection details for a vector map (interface to `v.db.connect -g').

Example:

>>> grass.vector_db('lakes')
{1: {'layer': '1', 'name': '',
'database': '/home/martin/grassdata/nc_spm_08/PERMANENT/dbf/',
'driver': 'dbf', 'key': 'cat', 'table': 'lakes'}}

Parameters:

map	vector map
args

Returns:

dictionary { layer : { 'layer', 'table, 'database', 'driver', 'key' }

Definition at line 37 of file lib/python/vector.py.

def python::vector::vector_db_select	(		map,
			layer = 1,
			kwargs
	)

Get attribute data of selected vector map layer.

Function returns list of columns and dictionary of values ordered by key column value. Example:

>>> print grass.vector_select('lakes')['values'][3]
['3', '19512.86146', '708.44683', '4', '55652', 'LAKE/POND', '39000', '']

Parameters:

map	map name
layer	layer number
kwargs	v.db.select options

Returns:

dictionary ('columns' and 'values')

Definition at line 172 of file lib/python/vector.py.

def python::vector::vector_history

(

map

)

Set the command history for a vector map to the command used to invoke the script (interface to `v.support').

Parameters:

map

mapname

Returns:

v.support output

Definition at line 136 of file lib/python/vector.py.

def python::vector::vector_info_topo

(

map

)

Return information about a vector map (interface to `v.info -t').

Example:

>>> grass.vector_info_topo('lakes')
{'kernels': 0, 'lines': 0, 'centroids': 15279,
'boundaries': 27764, 'points': 0, 'faces': 0,
'primitives': 43043, 'islands': 7470, 'nodes': 35234, 'map3d': 0, 'areas': 15279}

Parameters:

map

map name

Returns:

parsed output

Definition at line 148 of file lib/python/vector.py.

def python::vector::vector_layer_db	(		map,
			layer
	)

Return the database connection details for a vector map layer.

If db connection for given layer is not defined, fatal() is called.

Parameters:

map	map name
layer	layer number

Returns:

parsed output

Definition at line 79 of file lib/python/vector.py.

def python::vector::vector_what	(		map,
			coord,
			distance = 0.0
	)

Query vector map at given locations.

To query one vector map at one location

print grass.vector_what(map = 'archsites', coord = (595743, 4925281), distance = 250)

[{'Category': 8, 'Map': 'archsites', 'Layer': 1, 'Key_column': 'cat',
  'Database': '/home/martin/grassdata/spearfish60/PERMANENT/dbf/',
  'Mapset': 'PERMANENT', 'Driver': 'dbf',
  'Attributes': {'str1': 'No_Name', 'cat': '8'},
  'Table': 'archsites', 'Type': 'Point', 'Id': 8}]

To query one vector map at more locations

for q in grass.vector_what(map = ('archsites', 'roads'), coord = (595743, 4925281),
                           distance = 250):
    print q['Map'], q['Attributes']
                        
archsites {'str1': 'No_Name', 'cat': '8'}
roads {'label': 'interstate', 'cat': '1'}

To query more vector maps at one location

for q in grass.vector_what(map = 'archsites', coord = [(595743, 4925281), (597950, 4918898)],
                           distance = 250):
    print q['Map'], q['Attributes']

archsites {'str1': 'No_Name', 'cat': '8'}
archsites {'str1': 'Bob_Miller', 'cat': '22'}

Parameters:

map	vector map(s) to query given as string or list/tuple
coord	coordinates of query given as tuple (easting, northing) or list of tuples
distance	query threshold distance (in map units)

Returns:

parsed list

Definition at line 227 of file lib/python/vector.py.