Can a pyqgis script be run in QGIS?

Can a pyqgis script be run in QGIS?

PyQGIS scripts are great to automate spatial processing workflows. It’s easy to run these scripts inside QGIS but it can be even more convenient to run PyQGIS scripts without even having to launch QGIS. To create a so-called “stand-alone” PyQGIS script, there are a few things that need to be taken care of.

What do you need to know about pyqgis 101?

These are the basics of creating a Processing script that can be called from the Processing toolbox. PyQGIS 101 is a work in progress. I’d appreciate any feedback, particularly from beginners!

How to make a pyqgis script with osgeo4w?

An essential first step is to ensure that all environment variables are set correctly. The most reliable approach is to go to C:\\OSGeo4W64\\bin (or wherever OSGeo4W is installed on your machine), make a copy of qgis-dev-g7.bat (or any other QGIS version that you have installed) and rename it to pycharm.bat:

What are the mandatory functions in pyqgis processing?

Besides the constructor, our algorithm has to provide the following mandatory functions: name : Returns the unique algorithm name, used for identifying the algorithm. displayName: Returns the algorithm name that will be displayed in the Processing toolbox. createInstance: Must return a new copy of your algorithm.

Do you need PyQt4, Tkinter, or QGIS?

You don’t need here PyQt4, Tkinter or qgis.gui: you can create an application. You need here PyQt4 (and not Tkinter) and qgis.gui. I would like to program a standalone application using PyQGIS the way I can already program standalone applications using ArcPy.

Why is my standalone script not importing QGIS?

The issue does not appear to be that I have failed to import some Python package automatically imported by the QGIS application (qgis.core and qgis.utils) – I have those import statements in my standalone script, along with all the other package imports the script requires.

Is there a way to automate tasks in QGIS?

You can automate a lot of tasks in QGIS using Python scripting (PyQGIS) and the Processing Framework. Most of the time, you would run these scripts manually while QGIS is open. While that is helpful, many times you need a way to run this jobs via the command-line and without needing to open QGIS.

How to add a vector layer to QGIS?

Launch QGIS and go to Layer ‣ Add Layer ‣ Add Vector Layer. Browse to the folder containing the unzipped shapefiles and select the roads.shp file and click Open. First we must re-project the roads layer to a Projected CRS. This will allow us to use meters as units when performing analysis instead of degrees.

Is it possible to compile Python into a standalone executable?

It is recommended. Yes, it is possible to compile Python scripts into standalone executables. PyInstaller can be used to convert Python programs into stand-alone executables, under Windows, Linux, Mac OS X, FreeBSD, Solaris, and AIX. It is one of the recommended converters.

Why do algorithms run in a separate thread in QGIS?

By default, Processing runs algorithms in a separate thread in order to keep QGIS responsive while the processing task runs. If your algorithm is regularly crashing, you are probably using API calls which are not safe to do in a background thread.

What’s the difference between QGIS and standalone applications?

This leads me to believe that the difference is that the QGIS application correctly sets external environment variables, but those variables are not set properly when I run it as a standalone script.

How to ask your own question in pyqgis?

Asking for help, clarification, or responding to other answers. Making statements based on opinion; back them up with references or personal experience. To learn more, see our tips on writing great answers. Not the answer you’re looking for? Browse other questions tagged qgis pyqgis qgis-processing or ask your own question.

Where are the intermediate results stored in pyqgis?

When we want to convert this to a script, we need to take care of handling the intermediate results. Above, these intermediate results are stored in memory layers. The memory layer resulting from Extract by attribute is passed to the Buffer tool input as ‘MultiLineString?crs=EPSG:4326&…’.

How to chain processing tools in pyqgis script?

The memory layer resulting from Extract by attribute is passed to the Buffer tool input as ‘MultiLineString?crs=EPSG:4326&…’. For our script, we need to go a different way and store a reference to the result in a variable.

Where can I find the code in pyqgis?

After using the GUI, we can look up the corresponding code in the Processing history. It looks something like this: These code snippets from the Processing history provide us with a guide to the necessary syntax but we cannot use the code directly.

How to set up PyCharm with osgeo4w?

The following steps show how to set up PyCharm for stand-alone PyQGIS development on Windows10 with OSGeo4W. An essential first step is to ensure that all environment variables are set correctly.

How to use a map tool in QGIS?

Map tools should inherit from the QgsMapTool , class or any derived class, and selected as active tools in the canvas using the setMapTool () method as we have already seen. Here is an example of a map tool that allows to define a rectangular extent by clicking and dragging on the canvas.

Which is the most important widget in QGIS?

The Map canvas widget is probably the most important widget within QGIS because it shows the map composed from overlaid map layers and allows interaction with the map and layers. The canvas always shows a part of the map defined by the current canvas extent.

Where is Python-qgis.bat in Windows 10?

I’ve just been wrestling with a similar problem, and noticed a batch file in the OSGeo4W\\bin folder called python-qgis.bat. This is part of an OSGeo4W package based install of QGIS 2.18.15 x64 on Windows 10. When executed, this batch file opens the Python interpreter. import qgis successfully runs from within.

How to run QGIS in osgeo4w shell?

If you have installed QGIS via OSGeo4W, I suggest you to follow this work flow (I’ve just tested it on Windows 7): Open the OSGeo4W Shell. Start->All programs->OSGeo4W->OSGeo4W Shell. Set environment variables. My preferred way is to execute this bat file (updated 2016.11.03: this bat file) from the OSGeo4W Shell.

Which is the best way to develop in pyqgis?

This step basically installed the matching python version with the QGIS version you asked, QGIS in your python environment, all the depedencies that it needs (gdal, geos, psycopg2, sqlite, proj, numpy…), setted up the PYTHONPATH to dll and pyd files. So in just a few seconds you have all you need to develop in PyQGIS.

Why is init pyqgis not updated in cookbook?

It seems things changed to init PyQGIS but were not updated in the cookbook. There is a discussion about the issue. Look at the bottom of the discussion mainly. Be careful, it’s only a hint. It may be related to your Windows path too (working on Linux mainly).

How can I test my pyqgis workflow?

We’ll first use the GUI to run the corresponding tools (Extract by attribute, Buffer, and Extract by location) and test our workflow. Then we will go forward and create a PyQGIS version of the workflow. After using the GUI, we can look up the corresponding code in the Processing history.

How to run any processing algorithm via pyqgis?

Running any Processing algorithm via PyQGIS. Fixing topological errors in a vector layer. Geofabrik provides daily updated shapefiles of OpenStreetMap datasets. We will use shapefiles for Fiji for this exercise. Download the fiji-latest.shp.zip and unzip it to a folder on your disk.

How to run a QGIS processing algorithm in Python?

You can also run a QGIS Processing algorithm via Python using the processing.runAndLoadResults () function instead of processing.run () as shown above – which will load the result to QGIS canvas directly.

How to load a.bil file in QGIS?

Each layer is presented with a set of files .bil file containing the actual data, a .hdr file describing the data structure and a .prj file containing the projection information. QGIS can load the .bil file and provided the other files exist in the same directory.

What causes QGIS-python.exe to stop working?

In technical terms, it seems that you now need to instantiate the QApplication object before making the call to QgsApplication.initQgis () — the example program in the book instantiates the QApplication object after calling QgsApplication.initQgis (), which causes the program to crash.

How to import QGIS processing in stand-alone Python?

I want to write a few stand-alone scripts that use the processing toolbox of Qgis. I have read a few threads ( here and here, e.g.) but couldn’t find a working solution yet. Does anyone know what is missing for me to be able to import the processing module?