QGIS » QGIS Application

#!/usr/bin/env python

# -*- coding: utf-8 -*-

# define interface

##Virtual Layers (QGIS 2.x)=group

##Select by spatial relationship=name

##Layer_to_select_from=vector

##Spatial_relationship=selection Intersects;Contains;Within;Touches;Overlaps;Equals

##Intersection_layer=vector

##True_or_false=selection True;False

##Snapping_tolerance=string 1e-5

##Output_layer=string vl_

##Output_unique_identifier_column=string gid

##Output_geometry_column=string geom

from qgis.core import QgsVectorLayer, QgsMapLayerRegistry

# get input parameters from GUI

inlayer_select = processing.getObject(Layer_to_select_from)

spatial_rs = Spatial_relationship

if spatial_rs == 0:

        spatial_rs = 'ST_Intersects'

elif spatial_rs == 1:

        spatial_rs = 'ST_Contains'

elif spatial_rs == 2:

        spatial_rs = 'ST_Within'

elif spatial_rs == 3:

        spatial_rs = 'ST_Touches'

elif spatial_rs == 4:

        spatial_rs = 'ST_Overlaps'

elif spatial_rs == 5:

        spatial_rs = 'ST_Equals'

inlayer_intersection = processing.getObject(Intersection_layer)

t_or_f = True_or_false

snaptolerance = Snapping_tolerance

outlayer = Output_layer

outuic = Output_unique_identifier_column

outgeom = Output_geometry_column

# get geometry type and coordinate reference system from input layer ('Layer to select from')

ingeomtype = inlayer_select.geometryType()

if ingeomtype == 0:

    ingeomtype = 'point'

elif ingeomtype == 1:

    ingeomtype = 'linestring'

elif ingeomtype == 2:

    ingeomtype = 'polygon'

incrs = inlayer_select.crs().authid()

incrs = incrs[5:]

# create query

query_t = """SELECT

    DISTINCT('{0}'.rowid) AS '{4}',

    '{0}'.geometry AS '{5}'/*:{6}:{7}*/

FROM '{0}', '{2}'

WHERE {1}(ST_Snap('{0}'.geometry, '{2}'.geometry, {3}), ST_Snap('{2}'.geometry, '{0}'.geometry, {3}));

""".format( inlayer_select.name(), spatial_rs, inlayer_intersection.name(), snaptolerance, outuic, outgeom, ingeomtype, incrs )

query_f = """SELECT

    '{0}'.rowid AS '{4}',

    '{0}'.geometry AS '{5}'/*:{6}:{7}*/

FROM '{0}' LEFT JOIN '{2}'

ON {1}(ST_Snap('{0}'.geometry, '{2}'.geometry, {3}), ST_Snap('{2}'.geometry, '{0}'.geometry, {3}))

WHERE '{2}'.rowid IS NULL;

""".format( inlayer_select.name(), spatial_rs, inlayer_intersection.name(), snaptolerance, outuic, outgeom, ingeomtype, incrs )

if t_or_f == 0:

    query = query_t

elif t_or_f == 1:

    query = query_f

# run query and add layer to map

vlayer = QgsVectorLayer( "?query={}".format(query), outlayer, "virtual" )

QgsMapLayerRegistry.instance().addMapLayer(vlayer)