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Questions tagged [qgis-3.0]

For questions about Version 3.0 of QGIS

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0answers
38 views

PyQgis How could I open the “identify results” dock using “onSelectionChange()”

Using iface.mapCanvas().selectionChanged.connect(function) I'd like to open the Identify result dock for the selected feature as shown below: it could be manually done by selecting the feature with ...
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0answers
60 views

QGIS Girona 3.0.3 : CSV File and Georeferencing

I installed version 3.0.3 because I have to give lessons on this version but I meet several bugs compared to version 2.18. I would like to import a csv file. I do not have an error message but my ...
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0answers
44 views

QGIS3: How to set an attribute value?

I have written a python script which has one output line-vector layer. The python script should calculate some value and then the script should set the attribute (with that value) of a newFeature (...
1
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2answers
66 views

Getting field index from input vector layer in PyQGIS?

I am very new to QGIS3 and I am currently trying to convert a python script from QGIS 2.18 to QGIS 3. Therefore, I am trying to integrate my python script into the template from underdark -> see here ...
1
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0answers
18 views

Curved labels with data defined coordinates in QGIS

My goal: I want to have curved labels placed in the center of a linestring. I define the label position with the expression x: $x_at( num_points( $geometry)/2) y: $y_at( num_points( $geometry)/2) to ...
3
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1answer
86 views

Project CRS not being respected by QGIS

I have a button in a QGIS (3.4.1) plugin that should: create a new project; set it's CRS to EPSG:4326', then import various maps. However, when I run it for the first time after QGIS has loaded, the ...
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0answers
47 views

Creating a flow graph in QGIS 3.4

I attempting to make flow graph in QGIS 3.4, some thing like I have found several 'ways to do it' in QGIS 2.xx eg QGIS2.0 method I known its possible to get a line with arrows by just change the ...
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0answers
36 views

Vector Grid shows big difference between cartesian and ellipsoid measurement

I am using QGIS 3.4.1 on Windows 10. Project CRS is EPSG:3857 (WGS 84/Pseudo-Mercator). I have defined a vector grid. Type is Rectangle (polygon). Horizontal and vertical distance is 50 m. Overlay is ...
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0answers
41 views

Is there a QGIS 3 Implementation of Gravity/Huff model?

I tried to implement Jake's answer, but it depends on a plugin(rasterlang) that didn't port to QGIS 3. Is there QGIS 3 Implementation of this Huff model implemention? or Is there something ...
1
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3answers
41 views

Attribute errors with selectbylocation algorithm

Could anybody tell me what is wrong with execution of processing.run('qgis:selectbylocation', layer2, layer, u'intersect', 0) layer2 and layer is QgsVectorLayer object. This is error message I got
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0answers
29 views

Using QgsExpression in a custom validation?

We use our own validation in QGIS, which can be called from different areas of the plugin. In addition, reports can be generated from the results. Now we have switched to our own attribute forms in ...
-1
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0answers
142 views

ECW raster support for QGIS 3.4 and Ubuntu 18.04

I want to add ECW support to QGIS 3.4 on Ubuntu 18.04. I have not found a method to successfully add it.
1
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1answer
28 views

Changing txt layer Data Source in QGIS only using Python console?

I want to change the data source of a layer (non geometric, just a table of fields) created from a .txt file. I know how to do it manually but I want to do it with the Python console. I have tried the ...
4
votes
1answer
60 views

Measuring distance from gridsquares to contours of a shapefile

I have a baselayer (.shp file), with bathymetric contours. I want to measure the distance from each grid square in a grid, to the nearest nominated depth (so was hoping to have a way to also nomate ...
2
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0answers
163 views

How to Enable the QGIS Official Plugin Repository in the 3.4.1 Version?

I am using QGIS version 3.4.1. Recently, I cannot install new plugins. I have looked in the plugin setting. It seems that the link is blocked. The address is "https://plugins.qgis.org/plugins/plugins....
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0answers
47 views

Create points along line and apply a 90° offset to them - pyqgis

I want to create points along a line (works!) and then additionally move the points by a certain offset (perpendicular to the line) with pyqgis 3. See this sketch for further illustration: My ...
3
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2answers
106 views

Proportional Circles QGIS 3

In QGIS 3 there is the possibility to illustrate proportional data like population with circle of proportional size with the "assistant" option. But once in the print composer section, there is an ...
0
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1answer
81 views

Automatically refresh mapCanvas

In very simple beginners terms... is it possible to automatically refresh the QGIS map canvas in the background? I have a .geojson file with the data. This data changes (in case of a simulation) but ...
4
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0answers
144 views

qgz-projects can't be opened in QGIS 3

I have recently switched to QGIS 3.4.0 and currently, I can't open projects saved in .qgz-format. No error message, no crash, they simply don't open. When I try to load the project a second time, I ...
1
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0answers
20 views

SAGA_CMD.exe Bad image

In QGIS 3.0, 3.2 and now 3.4 I get the following error message saga_cmd.exe bad image C:\windows\system32\vcomp140.DLL is not designed to run on Windows or contains an error. I didn't have the ...
2
votes
1answer
55 views

How to resample QgsRasterLayer in QGIS 3?

I am generating png images of concentration maps, resulting from air quality modelling. Resulting files are croped and coverted to tiff files and than loaded into QGIS in Python: rlayer = ...
3
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0answers
146 views

Developing QGIS Python plugins using Jupyter?

Is it possible to run PYQGIS commands using Jupyter notebook and, if so, is there any documentation to develop QGIS plugins using Jupyter?
1
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1answer
36 views

Why isn't merge in QGIS working for me?

I am attempting to merge 153 geotifs into one large geotif of the Portland area. This is what my rasters looked like before the merge: Here is a zoomed in image: This is what the raster looks like ...
1
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1answer
60 views

Why does the algorithm shortestpathpointtopoint in QGIS3 using pyqgis only work in the second run?

A part of my skript uses the shortestpathpointtopoint algorithm, but it does only work in the second run (Python Console within QGIS). The discussed part of the script looks like points_lyr = ...
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0answers
21 views

Filtering Polygon Data

Working with QGIs 3.4.1 - Madeira I am trying to perform a simple Filter, but when I include more than 31 values of a given field I get Zero returns. Is there a limit. I am using the following ...
1
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1answer
78 views

How to edit geometry of multiple layers simultaneously in QGIS 3?

I have several line layers (route, pipes, cables) that share the same geometry and would like to edit them simultaneously. Is there a way to easily snap the geometry of the pipes and cables layers ...
1
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1answer
91 views

QGIS 3 - Change location of profile folder [duplicate]

My Windows user profile at work is stored on a network drive, which causes all kinds of trouble with QGIS. So I want to place it somewhere on my C:\ drive. I found out about --configpath, but that ...
2
votes
2answers
66 views

How to zoom to a specific loaded layer

I'm trying to zoom to a layer that was loaded with a script, just like manually would be done by right clicking the layer and pressing the "Zoom to Layer" button. I've tried several ways and the ...
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0answers
34 views

QGIS Export Webmap with QGIS2Web only using Python Console?

I want to automatically export my QGIS map to Webmap using only pyQGIS commands. By now I just know how to run the plugin with commands on python console: import qgis.utils qgis2web = qgis.utils....
1
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1answer
28 views

k-shortest path with QGIS

I am new to QGIS. I have a road network layer in QGIS. I can compute the shortest path between the two points over the road network layer via network analysis toolbox in QGIS. I am interested in ...
4
votes
0answers
41 views

Setting grid in QGIS that automatically adjust its intervals?

I am setting a template for multiple maps in QGIS 3 Layout and i was wondering if there is a way of automatically adjusting the grid's interval as a function of the scale of the map? I did a bit of ...
1
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0answers
65 views

gdal_merge.py not executing

When I type gdal_merge.py into Terminal, the output is -bash: gdal_merge.py: command not found. I installed 3.4.0 Madeira [from this link] for macOS 10.13 (https://www.qgis.org/en/site/forusers/...
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0answers
96 views

QGIS 3.4 ERROR:/bin/sh: 1: gdal_polygonize.py: not found

I am working with Xubuntu 18.04 Bionic and QGIS 3.4. When I try to convert raster to vector (polygonise) with GDAL command gdal_polygonize.py /home/tec/Documents/QGISdata/ADN_Avignon_DAB2018b/GeoTif/...
5
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0answers
75 views

Adding name of used coordinate system using alabel in QGIS Layout? [duplicate]

Is there a way to display the name of the used CRS in the layout? The expression "project_crs" displays the code of the used CRS but I'd like to use the common name of the reference systems. This ...
1
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2answers
84 views

Converting vector points to geo coordinate points

So I have an SVG file that has paths for a floor in a building. I want to convert these polygons into something like GeoJSON so that I can draw them in Mapbox. I already know the geo coordinates and ...
2
votes
1answer
69 views

Replacing Negative values with “0” for raster layer

I am trying to change negative values (raster layer) into "0" but I cannot find a way to do that. Does anyone know how to accomplish it in QGIS 3.2? I found an answer somewhere on the Internet to ...
1
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1answer
53 views

Draw rectangles with Shape Digitizing Toolbar and using a snapping function in QGIS 3

I draw rectangles with the Shape Digitizing Toolbar. In QGIS 3 there is a Snapping Toolbar which provides a snapping function. But unfortunately it is not possible to use both together. So whenever I ...
2
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0answers
35 views

Redrawing raster layer after file changed in QGIS?

I'm trying to find a way to redraw a raster layer after the original source file has been changed in QGIS 3.2+. However, it redraws only sometimes (~10%), which means there is some deep caching that I ...
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0answers
40 views

QGIS 3.0 input layers for Python script [duplicate]

I have just updated from QGIS 2.18 to QGIS 3 (Madeira) and I want to run a self-written Python script. My Python script has two input-layers which I usually imported with the processing.GetObject('...
1
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1answer
37 views

Textbox downsizes at printing in QGIS?

In QGIS 3.0 the print layout window shows the following: The result after pdf exporting is this: How can I prevent the downsizing?
1
vote
1answer
306 views

Draw rectangle in QGIS 3?

I want to draw a perfect rectangle. How can I do that with QGIS v.3+? Here is a possible way to draw a rectangle in old QGIS versions. Is there a similar solution for the latest QGIS version?
2
votes
1answer
60 views

How to use “Merge vector layers” in QGIS using Geopackages as output with FIDs duplicated

I'm using QGIS 3.2.3 in Windows and I created a tessellation with polygons (Voronoi tiling / Thiessen polygons) with the built-in tool "Voronoi Diagrams", (Call this layer LAYER1). Afterwards, I used ...
2
votes
0answers
242 views

QGIS 3.4.0 Madeira: unresponsive

I "upgraded" from 3.2.3 to 3.4.0 and it's so unresponsive it's unusable. The startup time is the same as 3.2.3, then it needs half a minute to build its UI. When I click on the UI, the reaction is ...
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0answers
27 views

Use ST_startpoint and linear referencing on a self intersecting linestring that includes a road interchange loop ramp

I have a linestring (representing a route along roads) that has a self-intersecting loop. As it has a self-intersecting loop it is not valid as a linestring. But I need it to be a linestring to ...
1
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0answers
67 views

Empty qgz when I open it

With QGIS 3.x when I save any project in a qgz format and I try to open it after, they are always with no one layers in the TOC (and canvas...). Every layer is in the same location in the computer... ...
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0answers
31 views

SumLineLengths in QGIS 3.2 not working?

I'm trying to use the Vector > Analysis Tools > Sum Line Lengths in QGIS version 3.2.3-Bonn. I'm inputting a ploygon (Multi Polygon) and a Lines (MultiLineString) shape files. I'm hoping to get the ...
1
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1answer
43 views

Add PostGIS layer to QGIS via Python Console

How can I add a PostGIS layer to QGIS via the Python Console? With some server setups, especially with a large number of tables, it can be very slow to load the list of layers via the Browser or Data ...
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0answers
50 views

No outputs created using processing-TauDEM and QGIS 3

Has anyone run across this error when trying the New processing-TauDEM plugin in QGIS 3? The following layers were not correctly generated: C:/Users/david.laverty/AppData/Local/Temp/...
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0answers
10 views

How to impose constraints on drop lists of two fields of the same layer?

Is it possible to impose with pyqgis3.0 some constraints on a drop list of a field attribute in order to govern the drop list attributes of another linked field? To better clarify this issue, I attach ...
2
votes
1answer
67 views

Autosizing all fields in a QGIS attribute table

Is there a way to autosize all fields in an attribute table? I am working with attribute tables that have over 50 columns and all of them have long names. Instead of autosizing single columns via ...