8
votes
Accepted
How to snap to items bounded within another layer in QGIS?
This you can achieve with the tracing tool, which is part of the snapping toolbar:
- 9,799
6
votes
Finding number of lines touching intersection point in polyline layer using QGIS
To count the touched split lines for each point, overlay_touches() can be used in combination with array_length().
The expression for creating the "type" integer field then looks like this:
...
- 1,197
6
votes
Accepted
Labeling count points within dissolved buffers in QGIS
What is a bit tricky: expressions work on a per-feature basis, so there is no direct way to only label the dissolved buffer (and any indirect way would be too complicated for the task, an overkill). ...
- 67.2k
6
votes
Labeling count points within dissolved buffers in QGIS
This isn't a complete answer but might provide you or others some ideas to combine with other suggestions.
Considerations:
Assumes you are OK with clustering algorithm approach (not necessarily same ...
- 10.8k
3
votes
Accepted
Interpolating polygon values based on neighbouring polygons in QGIS
You dont specify how you want to interpolate.
This buffers the grey polygons and use the surrounding polygons values to calculate the average, with the intersection areas as weights.
So a polygon with ...
- 68.8k
3
votes
Labeling count points within dissolved buffers in QGIS
If you want indeed to create one label per buffer, it is easier to indeed create dissolved buffers with the box Keep disjoint features separate checked to get one separate feature per "cluster&...
- 67.2k
3
votes
Splitting polygon that is result of difference function between two polygons in QGIS
Run multi to single-part, which splits multi-features into singular features for the whole layer.
- 15.7k
3
votes
Find all geometries in one table that do not exist in another
The plain = implementation for the GEOMETRY/GEOGRAPHY types directly compare their encoded byte sequences, which naturally is much faster than determining geometric likeliness, especially for higher ...
- 29.3k
3
votes
Select intersecting polygon in QGIS
Use "Select by Location":
"Select features from": your polygon layer
"Where the features": check "intersect"
"By comparing the features from": your ...
- 1,197
2
votes
Removing polygons from GeoDataFrame which do not intersect with any polygons of other GeoDataFrame using Python
There are many solutions, see Intersecting two shape problem using geopandas for example
Generally, iterrows should only be used in specific cases (How to iterate over rows in a DataFrame in Pandas)
...
- 54.4k
2
votes
Accepted
Removing polygons from GeoDataFrame which do not intersect with any polygons of other GeoDataFrame using Python
Spatial join is very fast. Try this:
import geopandas as gpd
import os
folder = r"/home/bera/Drives/data1/data/LMV/Topografi100/Topografi_100_Sverige_230721"
df1 = gpd.read_file(os.path....
- 68.8k
2
votes
Check if polygon falls inside other polygon with 2 layers
You can look for polygons partially contained by multiple country polygons, as in Zoltan's answer, or you can look for polygons that are fully contained by no country polygon.
SELECT *
FROM ...
- 40.7k
1
vote
Accepted
Check if polygon falls inside other polygon with 2 layers
To find polygons overlapped by more polygons from another layer you can use the following query.
SELECT a.identifier, a.name, count(*)
FROM layer_polygon a INNER JOIN layer_ countries c ON ST_Overlaps(...
- 7,245
1
vote
Accepted
Determine area enclosed by multiple segments
Solution for PostgreSQL/PostGIS.
Input geodata table named "linetoarea" shown in Figure 1 below.
Figure 1
Run Geo-SQL script:
WITH
noded AS (SELECT ST_Node(ST_Union(geom)) geom FROM ...
- 4,302
1
vote
Generating points inside each polygon based on colorful raster layers data with QGIS
Solution: the principle
Create a multiple of random points per area (like 100 times more than you want), then get the raster value for each point. Then select top or bottom 1% of these points, based ...
- 67.2k
1
vote
Creating raster layer with pixel values which are sum of overlapping polygons in single vector layer
Create a point or polygon grid with the desired resolution.
Create an attribute with the number of overlapping polygons for each grid point/cell. In QGIS, use the expression array_sum (...
- 67.2k
1
vote
Aggregating polygons within range between polygons and specific area using QGIS
It is not in QGIS, but if you can run python scripts you could try the (new) dissolve_within_distance feature of geofileops.
It offers a basic subset of features of "aggregate polygons". E.g....
- 471
Only top scored, non community-wiki answers of a minimum length are eligible