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.
In a previous article titled "「GIS Data」Chinese Geographic Region Partition Vector Data", we shared vector data on geographic region partitions. Recently, some users in our group requested geomorphological data. After searching, we actually found a 1:1,000,000 geomorphological type spatial distribution dataset from the Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences (CAS), and are sharing it with everyone.
When working with large raster datasets in QGIS, especially Float64 GeoTIFFs with hundreds of millions of cells, you may want to locate and zoom into the pixel that holds the maximum value. This can be useful in terrain analysis, remote sensing, or any context where the peak value matters.
A common approach involves converting the raster into a point or polygon layer. However, this is resource-intensive and often impractical for large datasets. This tutorial introduces an efficient alternative using PyQGIS and NumPy to directly zoom to the maximum value without raster reclassification or vectorization.
QGIS provides two methods for creating geometries using expressions: Geometry Generator (introduced in QGIS 2.14) and Geometry by Expression (introduced in QGIS 3.0). Both leverage QGIS's expression engine but serve fundamentally different purposes. This tutorial clarifies their differences and appropriate use cases.
In a previous article "Geo Hound: A Tool to Automatically Fetch Website Map Service Addresses", I introduced the powerful Geo Hound tool. Follow-up articles like "Get Hidden Government Map Data in 2 Steps (Geo Hound + Wuhan One Map)" and "Shanghai One Map Data (Trial)" shared practical experiences. Many readers subsequently asked: Can this map data be downloaded for offline use? While various methods exist, I'll share my two most-used approaches.
Recently in the Mala GIS group, someone raised an interesting question: Can GIS be used to analyze which province in China has produced the most leaders? Previously, you might have had to search via a search engine, but the data might not be up-to-date, and quantitative analysis would be cumbersome, requiring tedious data cleaning. However, in the AI era, we can easily accomplish this task using AI + GIS.
P.S.: This article is purely technical, and the data may not be entirely accurate. Corrections are welcome if any issues are found.
Extracting river/canal centerlines is a common task in GIS data processing. Users of ArcMap or ArcGIS Pro likely find it straightforward. Recently, many colleagues have started exploring QGIS, someone in My GIS Group asked about this, making it a good time to document the process.
PS: The author will focus on introducing methods to achieve ArcGIS-equivalent functions in QGIS. If you have specific needs in this area, feel free to leave a comment.
In a previous article "Practical Application of Geo Hound: Extracting Wuhan's Unified Planning Map Services for GIS Analysis", I demonstrated using Geo Hound to access Wuhan's planning map data in QGIS. A key objective was comparing land-use planning attributes against reality to identify discrepancies. While I mentioned using layer swipe for this comparison, many readers inquired about implementing swipe functionality in QGIS.
Following my previous article "This Certification is Highly Valuable for GIS Job Seekers, Yet Overlooked by Many", which helped numerous GIS professionals advance their careers, a middle school geography teacher recently requested vector data for China's geographic regional partitions for classroom presentations. After research, I'm sharing this valuable dataset.
Regions Included:
QGIS 3.44 has now been officially released. I downloaded and tried it out immediately. For Windows users, QGIS 3.44 offers both a test version with Qt6 support ("Latest Version for Windows (3.44) with Qt6 (experimental)") and the standard 3.44 version ("Latest Version for Windows (3.44)").
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