Diskussion:Workshop QGIS Python GeoPython 2017: Unterschied zwischen den Versionen
Stefan (Diskussion | Beiträge) K |
Stefan (Diskussion | Beiträge) K |
||
Zeile 10: | Zeile 10: | ||
* Functions aka system variables and "Singletons" like layer properties or number sequence (spcial Plugin needed?) | * Functions aka system variables and "Singletons" like layer properties or number sequence (spcial Plugin needed?) | ||
* Function for remote webservice: geocoding (reading from the internet) | * Function for remote webservice: geocoding (reading from the internet) | ||
+ | |||
+ | QGIS 2.18.x LTE | ||
+ | |||
+ | Where are Expression Functions used? | ||
+ | * Processing => Refactor fields | ||
+ | |||
+ | Use cases: | ||
+ | * z.B. env('USERNAME') | ||
+ | * Autoincrement / Sequence => QGIS 2.18 default Werte (QGIS 3 geplant) | ||
+ | * Add new (calculated) field | ||
+ | |||
Plugins: | Plugins: | ||
+ | * ExpressionPlus (for QGIS 2) | ||
* refFunctions | * refFunctions | ||
− | |||
* spatialJoin | * spatialJoin | ||
− | * AutoFields | + | * AutoFields (obsolete) |
+ | |||
+ | Writing: | ||
+ | * How to share a common Fn.? | ||
+ | ** Plugin | ||
+ | ** //Home/.qgis2/ python/ expressions / | ||
+ | ** (in Projekt) | ||
+ | * Debugging: | ||
+ | ** print | ||
+ | ** pdb | ||
+ | ** (Remote Debug Plugin) | ||
+ | * FAQ | ||
+ | ** How to store a value in PyQGIS? Use QSettings (/.qgis) or QGISProject (.qgs) | ||
Version vom 9. März 2017, 13:27 Uhr
See also
Custom Python Expression Functions for QGIS
Possible examples:
- Function reading from other feature properties
- Function reading from other layers (1:1)
- Functions aka system variables and "Singletons" like layer properties or number sequence (spcial Plugin needed?)
- Function for remote webservice: geocoding (reading from the internet)
QGIS 2.18.x LTE
Where are Expression Functions used?
- Processing => Refactor fields
Use cases:
- z.B. env('USERNAME')
- Autoincrement / Sequence => QGIS 2.18 default Werte (QGIS 3 geplant)
- Add new (calculated) field
Plugins:
- ExpressionPlus (for QGIS 2)
- refFunctions
- spatialJoin
- AutoFields (obsolete)
Writing:
- How to share a common Fn.?
- Plugin
- //Home/.qgis2/ python/ expressions /
- (in Projekt)
- Debugging:
- pdb
- (Remote Debug Plugin)
- FAQ
- How to store a value in PyQGIS? Use QSettings (/.qgis) or QGISProject (.qgs)
Notes:
Add attributes from a layer in the project or an external file (csv) to a layer (or the composer?) using insert expression? Create a custom expression python function to do this: http://nathanw.net/2012/11/10/user-defined-expression-functions-for-qgis/
How to import a user defined expression functions on QGIS start up. => Add them to qgis2/python/startup.py
Given polygon layer and a point one, calculate for each polygon feature, the number of points that it covers: https://lists.osgeo.org/pipermail/qgis-user/2016-October/038139.html http://gis.stackexchange.com/questions/212415/referencing-to-features-geometry-in-an-expression/212762#212762
Automatic Field Calculator Plugin: http://plugins.qgis.org/plugins/AutoFields/
Expressions Plus Plugin - Extra functions for the expression engine which didn't make it into QGIS 2.0: https://plugins.qgis.org/plugins/qgsexpressionsplus/
Resource Sharing Plugin (http://plugins.qgis.org/plugins/qgis_resource_sharing/) E.g. https://github.com/mara91/qgis_styles.git