Re: [Qgis-user] extracting vertices from a multipolygon using Field Calculator Function Editor
Thank you Stefan, I knew it would be as simple as that, but could not find it (the 'Java style' in the QgsGeometry class must have made me skip experimenting with that ) In Afrikaans (I am South African/Hungarian) there is a saying: 'As jy dom is, moet jy ...xxx' - and that was applicable to me in this case :-) I wrote the script yesterday in a freestanding (PyCharm) environment to solve the issue, as I needed to 'get it done', but this info is useful for future. Yesterday was the first time I was trying out the function editor and, just btw, a week or two back was when I first started writing QGis python scripts to solve work issues. So yes, I am struggling to find 'what is where' even though I am 10's of years down the road picturing the algorithm needed to solve my issue. My current challenge is also QGis Atlas with multiple sub-maps per page - but I am 'getting there' with some pointers received from this list. Thanks again for your response. Kind regards, Zoltan On 2021-10-19 08:14, Stefan Giese (WhereGroup) wrote: as a starting point: /from qgis.core import *// //from qgis.gui import *// // //@qgsfunction(args='auto', group='Custom', referenced_columns=[])// //def zCutBox(feature, parent):// // """// // Calculates vertices and return the x coordinate of the first as string// // """// // geom = feature.geometry()// // vertices = []// // for v in geom.vertices():// // vertices.append(v)// // return str(vertices[0].x())/ Am 18.10.2021 um 13:42 schrieb Zoltan: Hi Listers, I can't for the life of me work out the syntax/commands to use in the FieldCalculator->FunctionEditor for extracting vertices. I have a Polygon layer with Multipolygon rectangles at various rotations. I need to extract the 4 corner points so that I can calculate (and save in a virtual layer) lines that I can later use with "Processing->Split with lines". I will google for opening a new virtual layer and saving lines to it, but if that is quick and easy then some help there would also be welcome. Please can someone point me to a sample functions covering these requirements, or just fill in the gaps below. No, I'm not asking for someone to just write it for me. Thanks in advance, Zoltan [Having a brain-dead day :-( ] from qgis.core import * from qgis.gui import * @qgsfunction(args='auto', group='Custom', referenced_columns=[]) def zCutBox(feature, parent): vertices = blah blah return vertices[0][0] -- = Zoltan Szecsei GPrGISc 0031 Geograph (Pty) Ltd. GIS and Photogrammetric Services Cape Town, South Africa. Mobile: +27-83-6004028 (Signal, not WhatsApp) www.geograph.co.za = ___ Qgis-user mailing list Qgis-user@lists.osgeo.org List info:https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe:https://lists.osgeo.org/mailman/listinfo/qgis-user -- Mit freundlichen Grüßen Stefan Giese Projektleiter/Consultant - Schon gewusst? In unserem Blog geben wir Tipps & Tricks zu Open-Source-GIS-Software und berichten aus unserem Experten-Alltag: https://wheregroup.com/blog/ - WhereGroup GmbH Schwimmbadstr. 2 79100 Freiburg Germany Fon: +49 (0)761 / 519 102 - 61 Fax: +49 (0)761 / 519 102 - 11 stefan.gi...@wheregroup.com www.wheregroup.com Geschäftsführer: Olaf Knopp, Peter Stamm Amtsgericht Bonn, HRB 9885 -- = Zoltan Szecsei GPrGISc 0031 Geograph (Pty) Ltd. GIS and Photogrammetric Services Cape Town, South Africa. Mobile: +27-83-6004028 (Signal, not WhatsApp) www.geograph.co.za = ___ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
Re: [Qgis-user] extracting vertices from a multipolygon using Field Calculator Function Editor
as a starting point: /from qgis.core import *// //from qgis.gui import *// // //@qgsfunction(args='auto', group='Custom', referenced_columns=[])// //def zCutBox(feature, parent):// // """// // Calculates vertices and return the x coordinate of the first as string// // """// // geom = feature.geometry()// // vertices = []// // for v in geom.vertices():// // vertices.append(v)// // return str(vertices[0].x())/ Am 18.10.2021 um 13:42 schrieb Zoltan: Hi Listers, I can't for the life of me work out the syntax/commands to use in the FieldCalculator->FunctionEditor for extracting vertices. I have a Polygon layer with Multipolygon rectangles at various rotations. I need to extract the 4 corner points so that I can calculate (and save in a virtual layer) lines that I can later use with "Processing->Split with lines". I will google for opening a new virtual layer and saving lines to it, but if that is quick and easy then some help there would also be welcome. Please can someone point me to a sample functions covering these requirements, or just fill in the gaps below. No, I'm not asking for someone to just write it for me. Thanks in advance, Zoltan [Having a brain-dead day :-( ] from qgis.core import * from qgis.gui import * @qgsfunction(args='auto', group='Custom', referenced_columns=[]) def zCutBox(feature, parent): vertices = blah blah return vertices[0][0] -- = Zoltan Szecsei GPrGISc 0031 Geograph (Pty) Ltd. GIS and Photogrammetric Services Cape Town, South Africa. Mobile: +27-83-6004028 (Signal, not WhatsApp) www.geograph.co.za = ___ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user -- Mit freundlichen Grüßen Stefan Giese Projektleiter/Consultant - Schon gewusst? In unserem Blog geben wir Tipps & Tricks zu Open-Source-GIS-Software und berichten aus unserem Experten-Alltag: https://wheregroup.com/blog/ - WhereGroup GmbH Schwimmbadstr. 2 79100 Freiburg Germany Fon: +49 (0)761 / 519 102 - 61 Fax: +49 (0)761 / 519 102 - 11 stefan.gi...@wheregroup.com www.wheregroup.com Geschäftsführer: Olaf Knopp, Peter Stamm Amtsgericht Bonn, HRB 9885 ___ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
[Qgis-user] extracting vertices from a multipolygon using Field Calculator Function Editor
Hi Listers, I can't for the life of me work out the syntax/commands to use in the FieldCalculator->FunctionEditor for extracting vertices. I have a Polygon layer with Multipolygon rectangles at various rotations. I need to extract the 4 corner points so that I can calculate (and save in a virtual layer) lines that I can later use with "Processing->Split with lines". I will google for opening a new virtual layer and saving lines to it, but if that is quick and easy then some help there would also be welcome. Please can someone point me to a sample functions covering these requirements, or just fill in the gaps below. No, I'm not asking for someone to just write it for me. Thanks in advance, Zoltan [Having a brain-dead day :-( ] from qgis.core import * from qgis.gui import * @qgsfunction(args='auto', group='Custom', referenced_columns=[]) def zCutBox(feature, parent): vertices = blah blah return vertices[0][0] -- = Zoltan Szecsei GPrGISc 0031 Geograph (Pty) Ltd. GIS and Photogrammetric Services Cape Town, South Africa. Mobile: +27-83-6004028 (Signal, not WhatsApp) www.geograph.co.za = ___ Qgis-user mailing list Qgis-user@lists.osgeo.org List info: https://lists.osgeo.org/mailman/listinfo/qgis-user Unsubscribe: https://lists.osgeo.org/mailman/listinfo/qgis-user
