QGIS

Splitting many polygons into (almost) equal parts using a simple script in PyQGIS, the Python Console of QGIS

Whatever is your geo-thing, you may have come across a Polygon which needed to be split in half, three parts, five parts (a hundred parts?). Possible applications of the split polygons are performing zonal statistics and terrain parceling (agriculture).

The wedge tool: drawing circular quadrants, rings, and related geometries in QGIS

The input layer should be a point layer, in which there should be a point. The coordinates of this point should be the center of the circle (or wedge, or semi-circle). The default width of the wedge is 45°, or one-eight of a circle and the default azimuth of the wedge is 0°. The outer radius is what we are used to simply call a radius of a circle, and the inner radius variable will only be filled when we want to draw a ring or donut-like geometry.

Saving temporary scratch layers using PyQGIS and visualizing them in your QGIS Project

Since, I have been saving the generated files in scratch layers whenever they are intermediate products, of auxiliary nature to the process I am running. This way, they are automatically deleted, and I don’t have to worry about them after executing my code. So, I decided to summarize how I save PyQGIS tool outputs in scratch layers, in case this is useful to someone out there!

Quick workaround for PyQGIS error “file is not a directory” when saving files

This error is especially common when you are re-running a code you have already ran in the past. Sometimes, as I am coding, I run an incomplete version of my code, just to know if the compiler/interpreter accuses any errors. The codes frequently include open and saving items. I thought that the mentioned file would be overwritten every time I ran a file saving in the QGIS Python Console.

Solved: QGIS 3.20 Python Console shows an error when running Clip Vector by Extent tool

ERROR 1: Attempt to write non-multipoint (POINT) geometry to multipoint shapefile. ERROR 1: Unable to write feature 0 from layer points_layer. ERROR 1: Terminating translation prematurely after failed translation of layer points_layer (use -skipfailures to skip errors)

Sampling raster values in predetermined points on QGIS

In this post, I show how to perform this process using two different tools, one of them is native of QGIS, and the other is a plugin available on the plugin repository. Then, I comment on how to sample the original raster using an interpolation such as cubic, cubic spline, or bilinear for the sampled value.

Trick to fix broken polygon geometries in QGIS 3.X

First, I will create a purposefully invalid geometry to apply the fix. Then, I will show you two ways to fix it. In one of them, I simply apply the “Fix geometries” native tool of QGIS. The second option I will show here is using the buffer tool. In this simple trick, I will show you how to create an infinitesimal buffer around my broken geometry, which ends up fixing it, but has its perks as well.

How to use QGIS 3.20+ to generate outstanding river and drainage net map representations

The first thing I thought when I saw the “Interpolated Line” symbology (I described this functionality in another post) was that it would be useful to represent drainage networks. Today, that is what we are exploring. Innovative ways to represent your river network to depict the watershed in an even more elegant and informative way, using the “Interpolated Line” functionality.

How to create custom geometries based on vector shapes to use on the map legend or symbology on QGIS

This week, I am showing you how to create custom geometries to enhance your legends on QGIS Print Layout. Specifically, how to create these geometries based on vector files that you already have. The example I will provide is how to create the Legend Patch Shape for the state of Rio Grande do Sul, in Brazil.

A draggable Truesize Leaflet map of the Brazilian states, and how to do the same for your own country or region

The good news is that using Leaflet Truesize plugin, you can add your own customized draggable polygons to the map. A map that I thought almost immediately is the representation of the draggable Brazilian states, so you could compare them to each other and to the size of other countries. And that is why this is used as an example for this tutorial.