Hot answers tagged shapefile
As many users stated this question has no distinct answer. The results of an analysis may incomplete or fetch the wrong points, dependent on the definition of what should be considered as a corner. The simplest possibility would be the comparison of angles between adjacent points. As this question is familiar with this I will pick up this code fragment. ...
You should be able to dissolve based on the landcover attribute rather than area. This will dissolve adjacent polygons which share an attribute. You can then calculate the area of the polygons in the attribute table using the field calculator.
Thanks to the comment of @Ed Rollason I used the Topology checker to understand where was my problem. Ok, as I said, my layers overlap. But they overlap like a zipper (one on top of each other). After trying many tools (union, difference, merge, dissolve) without success, I found a video that explains the v.clean tool of the Process Toolbox. In QGIS ...
This is what fiona module would do, but in a sense you are then adding some GIS functionnalities to Python. Further GIS-like analysis on the geometries can then be performed using shapely.
This should normally work out of the box. Make sure that the imported GPX file layer is EPSG:4326 (lat/lon degrees). You can save it to the shapefile in any CRS you want. Please do not use Set Layer CRS in this step. For the Openstreetmap background, you can use the Openlayers plugin or the new QuickMap Services plugin. Openlayers requires the project CRS ...
After hours of trial and error, I found a solution that I answered here: How to merge and dissolve adjacent polygons and sum up their attributes in QGIS?
I'd check the following: first of all, I'd like to be sure that source data are OK, by comparing them with official/cadastral data I'd try to use the qgis openlayers plugin to check if the transformation to 3857/900913 works properly for both 23031 and 25831 Try to reproject using QGIS, just saving the shapefile with the target srid. If using QGIS works ...
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