Available as a 252-page paperback and a downloadable PDF.
Vector data consists of discrete features (points, lines, polygons). Use QgsVectorLayer to load shapefiles, GeoJSON, or GeoPackages: pyqgis programmer 39s guide 3 pdf work
from qgis.core import QgsField from PyQt5.QtCore import QVariant # Start editing session vector_layer.startEditing() # 1. Add a new attribute field vector_layer.addAttribute(QgsField("IsBigCity", QVariant.Int)) vector_layer.updateFields() # Refresh layer structure # Get field index for the newly created column field_idx = vector_layer.fields().indexFromName("IsBigCity") # 2. Update feature attributes based on a condition for feature in vector_layer.getFeatures(): if feature['pop_max'] > 1000000: vector_layer.changeAttributeValue(feature.id(), field_idx, 1) else: vector_layer.changeAttributeValue(feature.id(), field_idx, 0) # Commit changes to disk vector_layer.commitChanges() Use code with caution. 4. Working with Raster Layers Available as a 252-page paperback and a downloadable PDF
A step-by-step walkthrough for building your own QGIS plugins. Processing Toolbox: Add a new attribute field vector_layer
: QGIS uses its own bundled Python environment.
The native QGIS Processing framework exposes hundreds of algorithms (including GDAL, SGR, and Grass tools) directly to Python via the processing module. This eliminates the need to write complex geometry algorithms from scratch. Running a Buffer Tool