MalaGIS

Sharing GIS Technologies, Resources and News.

In the previous article titled "Displaying Selected Layer Count in QGIS with PyQGIS - MalaGIS", the author introduced a method to quickly view the number of selected layers using QGIS's Python API. However, if you need this functionality, you must open QGIS, then open the Python Console, locate the saved Python script file, and run it every single time. Although this process is simple, it can become tedious after repeated use. So, is there a way to automatically run a Python script when QGIS starts up? The author searched online and finally found a temporarily viable method to share today.

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When working with numerous layers in QGIS, it is often necessary to select multiple layers simultaneously for operations. However, with a large number of layers, it becomes difficult to quickly discern exactly how many are selected—don't worry, you can easily solve this by writing a small tool with PyQGIS!

Today, we share two methods to display the count of selected layers in real-time. These methods are straightforward to implement, with clear code, and can be tried by those in need.

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When working on data processing projects with ArcGIS Desktop (non-Pro version), extending arcpy functionality often requires installing third-party libraries. Since Python 2 doesn't include pip by default, this guide outlines the installation process.

Prerequisites

1. Install ArcGIS Desktop
2. Add Python path to environment variables (e.g., C:\Python27\ArcGIS10.X)
3. Remove other Python paths from system variables
   

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We're sharing the third edition of the bestselling book Python for Data Analysis, including complete sample code repositories, PDF version, and online access links.

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When extending ArcGIS Python functionality (e.g., using openpyxl for Excel integration), installing supplementary packages becomes necessary. This guide demonstrates manual and automated installation methods for both online and offline scenarios.

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Using Python within ArcGIS requires foundational Python knowledge. The following modules support Python integration:

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While developing a workflow involving spatial data duplication, an analyst requested help with client requirements:
① Convert individual polygons to WKT format in TXT files
② Merge multiple polygons into MultiPolygon WKT format

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This article summarizes common Python GDAL code snippets for geospatial data processing. GDAL (Geospatial Data Abstraction Library) is a foundational library for handling raster and vector geospatial data, maintained by the Open Source Geospatial Foundation (OSGeo). Implemented in C/C++, it provides Python, Java, and other language bindings. When calling GDAL's API in Python, the underlying execution relies on compiled C/C++ binaries.

GDAL Official Site: https://gdal.org/
Python API Documentation: https://gdal.org/api/index.html#python-api

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During development of a grid management system, I initially planned to use PostgreSQL for storing grid WKT data (for direct SHP export and map service publishing). Due to incompatibility with backend framework requirements, I switched to MySQL. This necessitated converting MySQL-stored WKT to Shapefiles. The solution: Java scheduled tasks invoking Python scripts to automate conversion. Below are the code implementations.

1. WKT to Shapefile Conversion

Preview:

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