Hi Marian,
I suppose the QGIS Clip algorithm does not work on "memory"-Layers, i.e.
Layers that are not written to disk. You can either try to save your
layer as a shapefile and then run the clipping algorithm, or iterate
over the geometries and use the QgsGeometry.Intersection(QgsGeometry)
function
(https://qgis.org/api/classQgsGeometry.html#a6ca0f918c7c67aff8ac9e0094707c99e).
This could be something like this (not tested, just off the top of my head):
clipPoly = clipLayer.getFeatures()[0].geometry() # get the first feature
(assumes only one polygon)
for input_feat in inputLayer.getFeatures():
input_geom = input_feat.geometry()
output_geom = input_geom.Intersection(clipPoly)
# do something with output_geom, e.g. write to a layer
Best regards,
Lukas
On 19.05.2017 16:02, Tudorache, Marian wrote:
*Hi,*
I have tried to run clipping processing algorithm and it fails.
First version:
srs = qgis.core.QgsCoordinateReferenceSystem(4019, qgis.core.
QgsCoordinateReferenceSystem.EpsgCrsId)
#Input Layer
inputLayer = qgis.core.QgsVectorLayer(shapeFileLocation +
“/inputLineString.shp”, “inputLineString”, “ogr”)
inputLayer.setCrs(srs)
Clipping Layer:
clipLayer =
qgis.core.QgsVectorLayer(“Polygon?crs={0}”.format(srs.authid())
#algorithm to add a clipping polygon feature
#the algorithm works because I tested with clipLayer.getFeatures() and
I was able to extract the geometry and points
…..
….
#calling processing algorithm.
processing.runalg(‘qgis.clip’, inputLayer, clipLayer, “output.shp”)
The error:
Unable to execute algorithm
Wrong parameter value: Polygon?crs=ESPG:4019
Any idea why is not working?
Thank you,
Marian
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Lukas Winiwarter TU Wien,
Stud. Ass. Department of Geodesy and
Tel: +43-(0)1-58801-12246 Geoinformation (E120),
Fax: +43-(0)1-58801-912246 Research Group Photogrammetry
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