Форумы GIS-Lab.info

Код: Выделить всё

##Polygon self symmetrical difference=name
##poly=vector
##polygonselfsymmetricaldifference=output vector
outputs_QGISADDUNIQUEVALUEINDEXFIELD_1=processing.runalg('qgis:adduniquevalueindexfield', poly,'diff_id',None)
outputs_SAGAPOLYGONSELFINTERSECTION_1=processing.runalg('saga:polygonselfintersection', outputs_QGISADDUNIQUEVALUEINDEXFIELD_1['OUTPUT'],'diff_id',None)
outputs_QGISEXTRACTBYEXPRESSION_1=processing.runalg('qgis:extractbyexpression', outputs_SAGAPOLYGONSELFINTERSECTION_1['INTERSECT'],'"ID" not like '%|%'',polygonselfsymmetricaldifference)

Код: Выделить всё

With CTE AS(
	SELECT '1' AS grp, st_union(st_intersection(a.geometry, b.geometry)) as geometry 
	FROM test a JOIN test b ON (
		(a.id < b.id)and
		(a.geometry is NOT NULL)and
		(b.geometry is NOT NULL)and
		(st_intersects(a.geometry, b.geometry))
	) 
	GROUP BY grp
) 
SELECT st_difference(test.geometry, CTE.geometry) FROM test
JOIN CTE 

Код: Выделить всё

from qgis.PyQt.QtCore import *

srcLayer = iface.activeLayer()
dstLayerName = 'SelfSymDifference'
idName = 'idSelfSymDifference'
srcLayer.startEditing()
myField = QgsField(idName, QVariant.Int )
srcLayer.addAttribute( myField )
srcLayer.updateFields()

idx = srcLayer.fieldNameIndex(idName)
i = 0
for f in srcLayer.getFeatures():
    f[idx] = i
    i += 1
    srcLayer.updateFeature( f )
srcLayer.commitChanges()

tpl = '''
With CTE AS(
    SELECT '1' AS grp, st_union(st_intersection(a.geometry, b.geometry)) as geometry 
    FROM %s a JOIN test b ON (
        (a.%s < b.%s)and
        (a.geometry is NOT NULL)and
        (b.geometry is NOT NULL)and
        (st_intersects(a.geometry, b.geometry))
    ) 
    GROUP BY grp
) 
SELECT st_difference(test.geometry, CTE.geometry) FROM %s
JOIN CTE'''

sql = tpl % (srcLayer.name(), idName, idName, srcLayer.name())

layer = QgsVectorLayer("?query="+sql, dstLayerName, "virtual")
QgsMapLayerRegistry.instance().addMapLayer(layer, True)