Questions tagged [qgis-3]

for questions specific to the 3.x series of QGIS.

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25 views

Finding mean and stdDev of vector layer field using PyQGIS [duplicate]

I am going to standardized a vector layer field in Python console in QGIS, for that I want to get mean value and stdev value of the field. How do I find mean and stdev in using PyQGIS. I tried this. ...
2
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2answers
65 views

QGIS3 symbology rule-based: use expression in string field for symbol

I have a shapefile that contains a string field and in there is an expression called 'Grabeland'. This expression is part of longer expressions but I only want to use the expression 'Grabeland' for ...
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1answer
24 views

Using PyQGIS in standalone scripts outside PyCharm and Spyder

Due to several reasons I sometimes want to use PyQGIS outside of QGIS, without using Python IDEs like PyCharm or Spyder. Am trying to run Python from the OSGeo4W Shell on Windows but am constantly ...
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0answers
19 views

Displaying multiple pictures on the same page in a QGIS3x Report

I am reporting on a project which has a series of transects around the perimeter of the site. For each transect I have prepared a detail plan and cross-section. Each transect is associated with a ...
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0answers
18 views

Creating Grid Layout with Letters and Numbers instead of coordinates using QGIS [duplicate]

Is there a possibility to create a grid layout in QGIS that does not section the map by coordinates but letters on the vertical axis and numbers on the horizontal axis? For better understanding, I ...
1
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0answers
22 views

Bundling Labels of Individual Features of same Shapefile

In my project, I have a shapefile with line geometry. Sometimes there are more than one lines that follow the exact same route like the others, but they differ in their description. I would like QGIS ...
0
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0answers
26 views

Clipped shapefile not appearing on screen using QGIS

I have just installed QGIS and I want to clip 1 polygon into the boundaries of another polygon. This seems like a simple thing to do and I use the clip tool to do so. However, when I click the zoom to ...
1
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0answers
23 views

Calculating distance between two points using QGIS C++ APIs

I have been trying to find the distance between two points using QGIS C++ APIs in Qt. I used the following code : QgsDistanceArea d; d.setEllipsoid("WGS84"); qDebug()<< "...
1
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0answers
34 views

Can QGIS label buffers have a different vertical size than the horizontal size?

I am producing a map which includes a narrow street with parallel boundaries. Down the centre of the street midway between the street boundaries and parallel to them is a line layer which is a ...
0
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0answers
39 views

Loading VRT using QGIS [closed]

I'm trying to open a VRT file into QGIS. But it isn't loading any VRT file. I assume that QGIS should be able to open this kind of file easily. When I try to open it (like any other vector file), is ...
2
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2answers
29 views

Differencing two rasters with very different resolutions (QGIS 3.20.3)

I am having a problem with analysing two rasters with 2 significantly different resolutions. Background on the two rasters: DEM is the ALOS_30m DEM which is in the WGS_84 format. Merged together ...
1
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1answer
44 views

TypeError: QgsGeometry.fromPolygonXY(): argument 1 has unexpected type 'QgsPolygon'

According to documentation: https://qgis.org/pyqgis/master/core/QgsGeometry.html?highlight=frompolygonxy#qgis.core.QgsGeometry.fromPolygonXY fromPolygonXY(polygon: object)→ QgsGeometry¶ Creates a new ...
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0answers
17 views

GDAL second order polynomial fails in Python but first order and thin plate spline work fine

I have Python code that will automatically georeference drone images regardless of overlap and without SfM software. The code runs without error when I set my transformation type to a first order ...
1
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0answers
27 views

PyQGIS: Load selected style categories with loadNamedStyle()

I would like to load a specific category of the default style of a layer. Layer and style are stored in a postgres database. The loadDefaultStyle function doesnt take arguments, so i tried this from ...
1
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0answers
35 views

QGIS3 crashes after exporting the second map in a for loop

I wrote a python script to produce a few maps automatically. I only have one layer, after the map production I change the style by loading a .qml-file and export the next map, and so on. I have 7 ...
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0answers
20 views

Moving elements together from two different layers

How can I move elements together from two different layers? I have to move element which consist of three separate elements on three separate layers. I attach a screenshot below. So is it possible? ...
1
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1answer
27 views

Callouts Line Style with PyQGIS

I'm trying to change colors and width of callouts using PyQGIS. Here is example of what i am trying to do : Here is my code to configure the labelling, including the callouts : ...
1
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1answer
27 views

Apply customization when the new project is loaded

I'm trying to apply customization settings to QGIS consistently at two moments: When QGIS opens; When new project (with some layers) is loaded. My code: from qgis.utils import iface from qgis.core ...
0
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1answer
112 views

Running standalone script into plugin with Button Click

Below code can be use to get the X,Y Coordinate of clicked location . class PrintSnappedPoint(QgsMapToolEmitPoint): def __init__(self, canvas): self.canvas = canvas ...
4
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1answer
89 views

Adding a point to an existing layer

How can I create a point from two coordinates with the QGIS Modeling tool and add it to an existing layer?
1
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1answer
27 views

How to match close-by coordinates of two layers in a "Join by location"?

I have two (point) layers with similar but not equal coordinates (e.g. 4.5432324 and 4.5432382) that represent data covering the same area (e.g. 1 km²). The attributes of very close-by points shall be ...
1
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0answers
49 views

Accessing QGIS using Jupyter Notebook

Using Python for QGIS in a Jupyter Notebook, how can I automate the task of importing a dxf file getting a data web service as a layer ? I have tried (https://lerryws.xyz/posts/Install-Jupyter-...
6
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1answer
84 views

Showing field name in the attribute table, not alias, in QGIS 3

I have a file geodatabase table added to QGIS. How can I show field name, not alias in the attribute table? (Or delete the aliases) In ArcMap I can set it in Layer Properties The name, set in ArcGIS ...
0
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1answer
88 views

Is it possible to host QGIS on a computing server?

I'm working on a project with QGIS Desktop 3.18.3. My plugin always crashes. Is it possible to host QGIS on a computing server? If so, will it improve the performance?
2
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1answer
33 views

Shortest path (point to point) in iteration, safe for the case there is no route

I am using Network Analysis > Shortest path (point to point) to compute the distance between two points, following a street network. Here is the code: n=0 for f1 in layer1: #Coordinates from ...
0
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0answers
34 views

Required DLL for calculating distance between 2 points

I have been trying to find the distance between 2 points using QGIS C++ APIs in Qt. I used the following code : QgsDistanceArea d; d.setEllipsoid("WGS84"); qDebug()<< "...
1
vote
2answers
49 views

Clipping polygons in one layer from larger polygon in another layer

In QGIS 3.16.10 I want to clip (remove) the polygon areas (yellow) in one layer from a larger polygon in another layer (gray). I've tried the Clip from the Processing Tool but it only returns the ...
3
votes
1answer
49 views

How to label parcels with multiple parcel owners in QGIS?

I have GeoPackage file with parcels (polygons) and an Excel table with parcel owners. As one parcel can have multiple parcel owners I established a one to many relationship. Now I wish to label the ...
4
votes
1answer
67 views

Distance matrix along line layer

I have a point layer which represent transport stops. Each stops have an id and the transport line id. I would like to have calculated the distance between every stops on the same transport line (...
0
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1answer
32 views

QGIS layer symbology strange - suddenly with lower opacity

I have a shapefile where I set the Symbology to categorized. After defining the symbols suddenly the symbols have less opacity while the opacity slider says 100%. Is this a bug in QGIS 3.10? Is there ...
3
votes
1answer
64 views

Locking layer styles in QGIS Print Layout using PyQGIS

I try to make a print-layout consisting of 2 maps-items. I only use one layer, but I want to picture it in different styles. First, as it is when loaded, and on the second map in another style (which ...
1
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0answers
12 views

QGIS v.net not working for certain lines data

I am trying to make a connected network using the v.net GRASS tool. It has worked for 3 vector line layers but is not working for two. I am not sure what the problem is. I used the same settings for ...
-1
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0answers
28 views

QGIS3 doesn't read umlaut from shapefile with encoding utf-8 [duplicate]

I have a shapefile where I set the encoding to UTF-8. The german umlaute ('') are shown with 1/2. The *.cpg file says UTF-8. Switching to encoding latin-1 doesn't help, I still don't have umlaute. ...
0
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0answers
12 views

QGIS fail to reconnect to ArcGIS Feature Services

I have a QGIS project which has some layers from an ArcGIS Feature Service. These work when first added. If I leave the project open overnight, the layers fail to render in the morning. If I simply re-...
2
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0answers
62 views

QGIS3 doesn't read umlaut from shapefile with coding UTF-8

I'm using shapefiles with encoding UTF-8 that were used in ArcGIS before. The German umlaut ( ¨ ) are shown as a question mark. In Layer Properties-->Source-->Settings the encoding is set to ...
0
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0answers
17 views

QGIS using model inputs and calculated attributes together in a model algorithm

Using QGIS 3.20.2 in the Processing Modeler I would like to use multiple fields as inputs in a dialogue box. One of those fields is calculated in a previous step. The other field is specified as an ...
2
votes
1answer
23 views

Disable image reloading in QGIS 3.16.10 georeference

I am trying to georeference an image (about 50mb and 20000x20000px), and every time I move the image or add a point it reloads/updates the image in georeference window and it takes about 1 minute to ...
0
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0answers
32 views

Buffer result differ with Shapely and QGIS

I am creating buffers using both Geopandas/Shapely (0.8.1/1.7.1) and QGIS (3.10.10). I see slight differences in the results with both software. I have a projection EPSG: 25832 in both software. I am ...
3
votes
1answer
64 views

Loaded shapefile isn't visible

I have a QGIS 3 project with EPSG code 25832 where there are shapefiles and and PostGIS layers. I added a shapefile consisting of *.dbf, *.qix, *.shp and *.shx files. This shapefile was used in ArcGIS ...
0
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0answers
36 views

Scale calculation PyQGIS

I need to calculate the scale for the selected polygons so that they fit into the given paper sizes. This should be calculated automatically, without user interaction. How can I do that?
4
votes
2answers
186 views

Add virtual field for vehicle speed to OSM roads (tag='Highway')

I want to add additional speed values to my OSM data. There is a maxspeed value for some of the roads, but a lot of values are 'null'. Therefore, I would like to add additional values based on the OSM ...
4
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0answers
44 views

QGIS Field Calculator NaN error messages dependent upon variable type?

I have a layer which contains roads. I am using the Field Calculator to compute some statistics based on different attributes. Using QGIS 3.10.14 I am running into an issue using lengths. I have ...
2
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2answers
60 views

Efficiently join two large point layers by location [closed]

I need to join two point layers containing several million points each. One has an ID and population density, the other has an ID and a settlement model (SMOD) categorization. The attributes of those ...
1
vote
1answer
35 views

Getting layer within a specific group using PyQGIS [closed]

I have two groups with unique names, which contain layers using identical names, e.g.: Group 1 Layer A Group 2 Layer A Is there a smart way to set the active layer to specifically Layer A from e.g....
1
vote
0answers
32 views

Why feature can't be edited in QGIS?

I am working with shapefiles in QGIS. At the moment I am editing a shapefile with line objects. When drawing a new line it appeared in a different manner then set in the layer properties. Now I can`t ...
3
votes
1answer
49 views

Formating timestamp correctly in QGIS

I am trying to automatically update timestamp of a feature from WFS-T connection in QGIS 3.16. According to the DescribeFeatureType, the attribute is defined as following: <xsd:element minOccurs=&...
1
vote
1answer
37 views

Exporting "user profile" to another machine in QGIS 3.20

How can I export the "user profile" in QGIS to use it on another machine?
2
votes
3answers
87 views

Reclassifying raster layer under condition

I have a raster layer with different landcover categories (on the left of the picture): What I need is a layer that holds the information if there is forest or not to later combine it with the ...
1
vote
0answers
18 views

How to measure distance between a polygon layer and a line layer in QGIS?

I have a polygon dataset that contains a handful of businesses. I also have an OSM roads line dataset. I am looking for the tool in QGIS that allows me to measure the distance from the polygon (either ...
1
vote
1answer
37 views

.prj not recognized in new QGIS again

When I try to open a shape file from statistik.at (an offical authority in Austria) the projection is not recognized correctly in QGIS 3.20.2 Odense. QGIS shows an "Unknown CRS". I can set ...

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