Hi again, unfortunately the processing is quite slow again with the difference algorithm, about 2,5 hours. With a script running with 60 iterations the total processing time will be about a week. No other processes are running except for internet. The script sequence is processing.runalg( 'qgis:difference', InputRoadNetwork, ClippingPolygon, OutputRoadNetwork ) I have tried the 'gdalogr:ogr2ogr' clipping algorithm expressed in http://darrencope.com/2011/03/31/clipping-large-shapefiles-using-ogr/ and http://www.gdal.org/ogr2ogr.html which I believe corresponds to the algorithm GDAL/OGR [32 geoalgorithms] => [OGR] Conversion => Convert format in the Processing Toolbox. Still I do not know how to get the code right in 'Creation Options'. It should be something like [-clipsrc ClippingPolygon.shp]. Anyone who has an idea?
Best regards, Jonas 2014-10-14 20:36 GMT+02:00 Jonas Sjögren <[email protected]>: > Hi, > to check that my data was ok I tried a clip tool in ArcMap where the same > calcuation took exactly 10 seconds. After some modifications in my script > and using the 'qgis:difference' algorithm, processing time was reduced to > about 5 minutes, quite acceptable. Thank you for helping me sort this out. > /Jonas > > 2014-10-14 7:47 GMT+02:00 Bernhard Ströbl <[email protected]>: > >> Hm, >> >> goes pretty fast here, both with PostGIS and shp layers (some 5 lines, 1 >> polygon, both layers in the same CRS as the project, shp on local drive) >> QGIS 2.4 64 bit on Win7 >> >> Bernhard >> >> Am 14.10.2014 02:49, schrieb Mike Flannigan: >> >> >>> I am also using QGIS 2.4 64b Chugiak on Windows 7. >>> The same thing happens to me. Even when I create >>> a line layer with only 11 lines and try to clip 3 >>> of them with a polygon layer, the progress bar just >>> goes back and forth for ever. >>> >>> I didn't run it for hours to see what would eventually >>> happen. >>> >>> Mike >>> >>> >>> I might be doing something wrong. >>> >>> On 10/13/2014 8:02 AM, [email protected] wrote: >>> >>>> Hi, >>>> I am trying to clip a road network by a polygon in a script using the >>>> algorithm 'qgis:clip'. The result seems to be quite ok but it takes an >>>> incredible long time to produce, about 14 hours (!). The road network >>>> shapefile consists of about 5000 features (not very many, I believe) and >>>> the clipping shapefile consists of one single polygon. When using >>>> Vector => >>>> Geoprocessing Tools => Clip from the QGIS menu, the time required is >>>> about >>>> the same. Does anyone have a clue why it takes so long time? Are there >>>> other clip tools that I may try? I?ve been looking at the >>>> 'gdalogr:ogr2ogr' >>>> algorithm and its clipsrc function but not got it to work properly >>>> yet. I?m >>>> using QGIS 2.4 Chugiak on Windows 7 with 2.5 GHz processor. Thankful for >>>> all hints that may help, >>>> /Jonas >>>> >>> >>> >> >> __________ Information from ESET Mail Security, version of virus >> signature database 10558 (20141014) __________ >> >> The message was checked by ESET Mail Security. >> http://www.eset.com >> >> >> >> _______________________________________________ >> Qgis-user mailing list >> [email protected] >> http://lists.osgeo.org/mailman/listinfo/qgis-user >> > >
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