After having tried to explain in a simple way some Basic rules for writing Python scripts for Processing Toolbox in QGIS, this time we will discover the basic rules for writing custom functions in QGIS using the Function Editor. QGIS allows the definition of user-defined expression functions (in Python or C++) from the Function Editor tab […]
Read more "How to create custom functions in QGIS using the Function Editor"Posts with the [Quick Coding Tip] tag are thought for giving a quick solution to simple PyQGIS tasks. If you already know How to load a layer in QGIS using Python, you may run the following code: for getting the extent of a vector or raster layer. Instead, using this code: you will get the […]
Read more "[Quick Coding Tip] How to get the extent from a vector or raster layer in QGIS using Python"In this task, we will use python scripting for converting a Comma-Separated Values file (also known as CSV file) to a shapefile using PyQGIS. We will use a sample dataset available from SpatialKey, which contains: 36634 records in Florida for 2012 from a sample company that implemented an aggressive growth plan in 2012. We will only use […]
Read more "How to convert a CSV file to a shapefile in QGIS using Python"Posts with the [Quick Coding Tip] tag are thought for giving a quick solution to simple PyQGIS tasks. If you already know How to load a layer in QGIS using Python, you may run the following code: for getting the total number of features that are stored in the current vector layer. Instead, if you […]
Read more "[Quick Coding Tip] How to count the features from a vector layer in QGIS using Python"One of the most powerful QGIS tools is the possibility to create custom Python codes and then adding them to the Processing Toolbox. This operation has several advantages, for example: the creation of user-friendly dialogs for the user inputs and output files; the integration of the custom script with other tools already loaded in the […]
Read more "Basic rules for writing Python scripts for Processing Toolbox in QGIS"This task is based on my answer to this question from gis.stackexchange.com. Sometimes it happens that, when importing external files in QGIS (typically .CSV files), the fields specifying the longitude and latitude coordinates are accidentally inverted: this behavior will produce a different result in respect of the desired output. If we don’t want to repeat the same procedure, we may run a […]
Read more "How to invert lon/lat coordinates in QGIS using Python"This task is based on my answer to this question poped up on gis.stackexchange.com. Starting from a raster layer, the goal for this task is to split it in several tiles for further processing. We can do this task by directly using QGIS, or even with Python (GDAL). More in detail, we want to split a 5×5 […]
Read more "How to split a raster in several tiles using QGIS or Python (GDAL)"This task is based on my answer to this question poped up on gis.stackexchange.com. We start from one point vector layer and one line vector layer: the goal for this task is to literally “snap” the line vector layer to the nearest points on the basis of a searching distance (i.e. we want to snap the line to the points which are […]
Read more "How to snap lines to points in QGIS using Python"In this task we will use python scripting to count the number of duplicate geometries from a point vector layer and store the result in a memory layer. Starting, from something like this (overlapping points are not visible!): we will see how it’s easy (and fast) to do the task using a QgsSpatialIndex. The first […]
Read more "How to count duplicate points in QGIS using Python"In this task we will use python scripting to count the number of points which lie inside a polygon and store the result in a memory layer. The Processing algorithm Count points in polygon does the same thing, but we want to do the task without using it. We will use two datasets available from Natural Earth: the first one […]
Read more "How to count points in polygons in QGIS using Python"
"How To" in QGIS 