Add an easy way to access (read/write) to the attributes of a geometry feature in a vector map

git-svn-id: https://svn.osgeo.org/grass/grass/trunk@54043 15284696-431f-4ddb-bdfa-cd5b030d7da7

lib/python/pygrass/vector/__init__.py

@@ -295,7 +295,8 @@ class VectorTopo(Vector):
         """
         if vtype in _GEOOBJ.keys():
             if _GEOOBJ[vtype] is not None:
-                return (_GEOOBJ[vtype](v_id=indx, c_mapinfo=self.c_mapinfo)
+                return (_GEOOBJ[vtype](v_id=indx, c_mapinfo=self.c_mapinfo,
+                                       table=self.table)
                         for indx in xrange(1, self.number_of(vtype) + 1))
         else:
             keys = "', '".join(sorted(_GEOOBJ.keys()))
@@ -362,7 +363,8 @@ class VectorTopo(Vector):
                 return GV_TYPE[ftype]['obj'](v_id=feature_id,
                                              c_mapinfo=self.c_mapinfo,
                                              c_points=c_points,
-                                             c_cats=c_cats)
+                                             c_cats=c_cats,
+                                             table=self.table)
         else:
             raise ValueError('The index must be >0, %r given.' % feature_id)
 

lib/python/pygrass/vector/abstract.py

@@ -72,7 +72,7 @@ class Info(object):
         >>> municip.close()
 
     """
-    def __init__(self, name, mapset=''):
+    def __init__(self, name, mapset='', link_id=None):
         # Set map name and mapset
         self._name = name
         self.mapset = mapset
@@ -81,6 +81,7 @@ class Info(object):
         self._class_name = 'Vector'
         self.overwrite = False
         self.date_fmt = '%a %b  %d %H:%M:%S %Y'
+        self.link_id = link_id
 
     def _get_name(self):
         if self.exist() and self.is_open():
@@ -259,6 +260,18 @@ class Info(object):
         if openvect == -1:
             str_err = "Not able to open the map, C function return %d."
             raise OpenError(str_err % openvect)
+        # istantiate the table
+        self.table = self.get_table(link_id=self.link_id)
+
+    def get_table(self, link_id=None, link_name=None,):
+        if link_id is None and link_name is None and len(self.dblinks) == 0:
+            return None
+        if link_id is not None:
+            return self.dblinks.by_number(link_id).table()
+        elif link_name is not None:
+            return self.dblinks.by_name(link_name).table()
+        else:
+            return self.dblinks.by_number(1).table()
 
     def close(self):
         if self.is_open():

lib/python/pygrass/vector/geometry.py

@@ -6,13 +6,15 @@ Created on Wed Jul 18 10:46:25 2012
 
 """
 import ctypes
-import numpy as np
 import re
 
+import numpy as np
+
 import grass.lib.gis as libgis
 import grass.lib.vector as libvect
 
 from basic import Ilist, Bbox, Cats
+import sql
 
 
 WKT = {'POINT\((.*)\)': 'point',  # 'POINT\(\s*([+-]*\d+\.*\d*)+\s*\)'
@@ -107,6 +109,64 @@ def get_xyz(pnt):
     return x, y, z
 
 
+class Attrs(object):
+    def __init__(self, v_id, table):
+        self.id = v_id
+        self.table = table
+        self.cond = "%s=%d" % (self.table.key, self.id)
+
+    def __getitem__(self, key):
+        """Return the value stored in the attribute table. ::
+
+            >>> attrs = Attrs(v_id, table)
+            >>> attrs['LABEL']
+            .
+
+        .."""
+        #SELECT {cols} FROM {tname} WHERE {condition};
+        cur = self.table.execute(sql.SELECT_WHERE.format(cols=key,
+                                                         tname=self.table.name,
+                                                         condition=self.cond))
+        return cur.fetchone()[0]
+
+    def __setitem__(self, key, value):
+        """Set value of a given column of a table attribute. ::
+
+            >>> attrs = Attrs(v_id, table)
+            >>> attrs['LABEL'] = 'New Label'
+
+        .."""
+        #UPDATE {tname} SET {new_col} = {old_col} WHERE {condition}
+        self.table.execute(sql.UPDATE_WHERE.format(tname=self.table.name,
+                                                   new_col=key,
+                                                   old_col=repr(value),
+                                                   condition=self.cond))
+        #self.table.conn.commit()
+
+    def __dict__(self):
+        """Reurn a dict of the attribute table row."""
+        dic = {}
+        for key, val in zip(self.keys(), self.values()):
+            dic[key] = val
+        return dic
+
+    def values(self):
+        """Return the values of the attribute table row."""
+        #SELECT {cols} FROM {tname} WHERE {condition}
+        cur = self.table.execute(sql.SELECT_WHERE.format(cols='*',
+                                                         tname=self.table.name,
+                                                         condition=self.cond))
+        return cur.fetchone()
+
+    def keys(self):
+        """Return the column name of the attribute table."""
+        return self.table.columns.names()
+
+    def commit(self):
+        """Save the changes"""
+        self.table.conn.commit()
+
+
 class Geo(object):
     """
     >>> geo0 = Geo()
@@ -114,7 +174,8 @@ class Geo(object):
     >>> cats = ctypes.pointer(libvect.line_cats())
     >>> geo1 = Geo(c_points=points, c_cats=cats)
     """
-    def __init__(self, v_id=None, c_mapinfo=None, c_points=None, c_cats=None):
+    def __init__(self, v_id=None, c_mapinfo=None, c_points=None, c_cats=None,
+                 table=None):
         self.id = v_id  # vector id
         self.c_mapinfo = c_mapinfo
 
@@ -130,6 +191,10 @@ class Geo(object):
         else:
             self.c_cats = c_cats
 
+        # set the attributes
+        if table:
+            self.attrs = Attrs(self.id, table)
+
     def is_with_topology(self):
         if self.c_mapinfo is not None:
             return self.c_mapinfo.contents.level == 2