What do you need to know about pyqgis development?
Raster Layers 3.3. QgsProject instance 4. Accessing the Table Of Contents (TOC) 4.1. The QgsProject class 4.2. QgsLayerTreeGroup class 5. Using Raster Layers 5.1. Layer Details 5.2. Renderer 5.3. Query Values 6. Using Vector Layers 6.1. Retrieving information about attributes 6.2. Iterating over Vector Layer 6.3. Selecting features 6.4.
How to use QGIS in a virtual layer query?
Functions of QGIS expressions can also be used in a virtual layer query. To refer the geometry column of a layer, use the name geometry. Contrary to a pure SQL query, all the fields of a virtual layer query must be named. Don’t forget to use the as keyword to name your columns if they are the result of a computation or function call.
How to create a vector layer in pyqgis?
Selecting features 6.4. Modifying Vector Layers 6.5. Using Spatial Index 6.6. The QgsVectorLayerUtils class 6.7. Creating Vector Layers
How to create a new GeoPackage layer in QGIS?
QGIS will automatically add the new layer to the legend, and you can edit it in the same way as described in section Digitizing an existing layer. Further management of SpatiaLite layers can be done with the DB Manager. See DB Manager Plugin. To create a new GeoPackage layer go to Layer ‣ New ‣ New GeoPackage Layer… .
When to run Python code in pyqgis 1.3?
1.3.2The PYQGIS_STARTUP environment variable ouY can run Python code just before QGIS initialization completes by setting the PYQGIS_STARTUP environment ariablev to the path of an existing Python \le. This code will run before QGIS initialization is complete.
Where do I find QGIS resources in pyqgis?
PyQGIS custom applications or standalone scripts must be con\gured to locate the QGIS resources, such as projection information and providers for reading vector and raster layers. QGIS Resources are initialized by adding a few lines to the beginning of your application or script.
Is there an aComplete QGIS apireference for Python?
There is acomplete QGIS APIreference that documents the classes from the QGIS libraries.The Pythonic QGIS API (pyqgis)is nearly identical to the C++ API. A good resource for learning how to perform common tasks is to download existing plugins from the plugin repositoryand examine their code. 1