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Dynamic stats in the decoration title lable, by time stamp, in QGIS

Your issue is that the filter of your aggregate function is not a filter, but only an attribute. You need to add a comparison to actually make it a filter. Something like: aggregate('Lake','mean',&...
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2 votes
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QGIS converting text field with special characters to numeric (real) field

regexp_substr( "stringfield", '(-?\\d+\\.?\\d*)') https://www.tutorialspoint.com/How-to-extract-numbers-from-a-string-in-Python
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1 vote

Polygonize/Vectorize large raster

I would point out the a 47000 x 37000 pixel raster contains 1.7 billion pixels. If your binary raster is mostly "salt and pepper" (1's and 0's not clustered into contiguous areas) then you ...
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Separate canopy from ground - based on DEM generated from thermal imaging

Producing a canopy height model (CHM) is a well established procedure, so I don't think you will need to "re-invent the wheel" in python or Matlab. See, for example: from the pyfor package ...
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Exporting raster of a map to QGIS from GGplot in R

Your question reminds me of a quote from a smart fellow: "You're trying to get back the fish after making fish soup". You should be saving to a "*.tif" raster file the density that ...
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1 vote

Is there an Offset function in QGIS for Polygons?

If you just want your polygon shape to render offsetted, you could define the symbol with a Geometry Generator with the code : offset_curve( line_merge( exterior_ring( force_polygon_ccw( $...
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0 votes

Attribute form constraint, using NULL

It does not work the way we imagined. We falsly assumed that the return-value from the expression nullif("interior_observed", false) would be assigned to the field content. My guess now is ...
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5 votes
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Making new field with formatted values in QGIS

Try this expression: substr("Kiinteistötunnus",0,3) ||'-'|| substr("Kiinteistötunnus",4,3) ||'-'|| substr("Kiinteistötunnus",7,4) ||'-'|| substr("Kiinteistötunnus&...
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4 votes
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QGIS doesn't like the number 6?

I think the offset of 0.1 millimeters that you are using at the moment might be too small, I tried with a random set of polygons using "Outside Polygons" as a Mode and 0.1 millimeters as the ...
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1 vote

Adding a fixed table to layout in QGIS

Late to the party but an answer composerTitle = 'Layout 1' project = QgsProject.instance() projectLayoutManager = project.layoutManager() # Access to the layout by name layout = projectLayoutManager....
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Export PNG in QGIS, same extent but outputs are not exactly the same

Try using a Print Layout. When you can create a map in a layout, you can specify it's dimensions by accessing it's properties (1). Pan the map location as desired, export as image (2), select PNG as ...
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2 votes

QGIS - copy/paste symbology labels

Your symbology can be loaded by clicking on the three dots next to Delete All button(On the Layer Properties window, Symbology section) option -Load Color Map from File...-. The file must have ...
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1 vote
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When moving layer labels the labels connect

You need to choose a unique key. The window for this pops up the first time you move a label: You cannot use an expression here. So in case you do not have one, you need to add it to the layer first. ...
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1 vote

How to draw a scale or a graduated marker on QGIS?

One way to do it would be to trace a line perpendicular to your polygons then use the "Points along geometry" tool to place regularly spaced points on it. This way your points will be ...
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2 votes
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Exporting layer with datetime field with milliseconds value

If you register a custom formatter as described in my answer on your related question (Displaying milliseconds in Attribute Table using PyQGIS), the formatter can be applied to modify the exported ...
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0 votes

Displaying only points within polygon I created in QGIS

Use symbolgy and assign the function 'geometry' as below: pole_of_inaccissibilty($geometry,1) or use the plugin Point sample tools.
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1 vote

How to set default attribute values on a new line based on overlay_touches/nearest for start_point and end_point

With your first expression, if you are getting NULL in the preview when setting up the default expression, this is normal if you have no features in your layer (or if all of the existing features ...
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1 vote

Clip Line Layer to Polygon but retain the Lines outside the polygons

If your aim is to only keep the lines that do not intersects the polygons you could use the "extract by location" tool. Layer to select from : your line layer Additional layer : your polygon ...
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4 votes
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I don't see menu in QGIS Print Layout for enabling atlas, or browsing through atlas pages

That's probably because you've created a new Report (Project > New Report) and not a new Print Layout (Project > New Print Layout) As far as I know atlases are not available in Reports.
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2 votes
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QGIS - Group by expression in attributes form completion

Try using this expression (QGIS 3.22) in the 'Filter expression' part of your Value Relation widget - $id=array_first(array_agg($id,"culture")) It groups the feature id value from the other ...
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0 votes

Is it possible to overline labels / text / strings in QGIS 3.x?

Can you share how you've configured your rule-based labels to appear in those exact positions relative to each other? (did you use specific offsets?) Since you want these to be separate labels with ...
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  • 7,329
0 votes

Clip features of lines based on parameter from another shapefile (Polygon)

You can do this using pyQGIS: canvas = iface.mapCanvas() # first, define the map canvas by referencing iface layers = canvas.layers() # gather all layers into a list for lyr in layers: # loop through ...
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Merge a .gpx with a DEM

Run Menu Raster > Conversion > Rasterize the line. Set the value for A fixed value to burn to 10 and define Output raster size units (either pixels or layer units) and set the resolution you ...
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1 vote

Changing editing capabilities on MapInfo *.tab file using QGIS?

FYI...It seems that you can edit MapInfo .tab files as long they are not using .dbf to store the data. Doesn't look like it can edit those...I tested and I can edit with a .dat file, but not a .dbf ...
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2 votes
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How can I activate GeoTIFF compression in QGIS 3.x gdal_translate?

Try 'OPTIONS':'COMPRESS=JPEG|JPEG_QUALITY=60' I executed the tool manually in QGIS, pressed Ctrl+Alt+H to see the command syntax:
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7 votes
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QGIS - Connection Lines using geometry generator between 2 layers in a relation N-1

You can do this using array_foreach() function collect_geometries(array_foreach(string_to_array( "ID_UC" ), Use this expression on the 'concpoints' layer. collect_geometries(array_foreach(...
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1 vote

How do I change my view to nadir in QGIS?

I had the wrong CRS. After searching through, and trying several of the WMS services with NADIR imagery mentioned by Vince without significant changes, I tried making a new project altogether and ...
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Problems with uploading point coordinate British National Grid data into QGIS as .csv file

The "NT 9791" format would be a 1km x 1km square. You can download shapefiles here: https://github.com/charlesroper/OSGB_Grids/find/master As for the 6-digit number, I don't know.
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6 votes

What is meant by 'current feature' when using the field calculator or expression builder in QGIS?

The current feature is the one you're doing the calculation for. If you e.g. selected a single feature on the layer and choose to only updated selected features, the area is only calculated for that ...
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4 votes
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Use point symbology tools in geometry generator of a polygon

You can use the Diagrams tab for this. Go to Layer Pproperties > Diagrams, then: Choose a Pie Chart Add your value field to the attributes list Within Size menu choose "Scaled Size" with ...
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1 vote

Clipping large shapefile using QGIS

In QGIS try: 1 Fix geometries, save the output as geopackage. 2. Create spatial index. 3. Clip If it still doesnt work. 3. Multipart to Singlepart the output. 4. Create spatial index, 5. Clip
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1 vote

QGIS: update query in db-manager fails

Ok, new day, fresh brain, solution is easy: the error message reveals that I had attempted to change the database from the wrong angle: I had been trying to change table content while being connected ...
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1 vote

"One or more line ignored due to geometry not having a minimum of three vertices" error when "Line to Polygon" in QGIS

I could get the same error "One or more line ignored due to geometry not having a minimum of three vertices" when I was trying to apply the "Lines to polygons" geoalgorithm for ...
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2 votes

QGIS difference operation extremely slow

Have you tried setting a spatial index? For some algorithms in QGIS this makes a large difference in the time to completion.
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0 votes

Getting base Line of PostGIS skeleton

A simple approach to "trim the branches" could be by longitude but is not a complete solution. with lines as ( SELECT st_subdivide( st_straightskeleton( ST_GeomFromText('POLYGON (( 190 190, ...
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1 vote
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Clip features of lines based on parameter from another shapefile (Polygon)

Try this way: Calculate a field for the overlay layer that contains the id (i will call it id, you can use this expression $id to get the id). Intersect your base layer with the 25.1.19.4. ...
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0 votes

Split TIFF and shapefile into smaller parts

This is my first project with geo data and for some reason I thought if I split the tif I must do the shape at the same time, so there should be a command to do just that. My solution: Created a grid ...
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1 vote

Creating Network Flow Diagram using QGIS

In my opinion, you should start with the telecom project you are working on. Next, for sure you will find the layers you need to include in your network flow schematic. You can follow the steps: ...
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2 votes

Is it possible to style the QGIS Message Bar using QSS?

Meanwhile, in QGIS 3.22 it works. I got it with that code: QFrame QFrame { min-height: 70px; margin:0px; padding:0px; } QLineEdit { border: 1px solid gray; border-radius: 1px; padding: 0 8px; ...
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1 vote
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Load raster from Requester-Pays S3 bucket into QGIS

I was able to achieve this by setting the Gdal environment variable AWS_REQUEST_PAYER=requester in the same place as the others above.
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1 vote

Is it possible to create Rule-Based Styling with $geometry intersecting a second layer?

Yes, it is possible. In the 'rule based' symbology, choose the rule to be: intersects($geometry, geometry(get_feature('layer name', 'attribute field name', 'value'))) Let's say you want your layer to ...
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4 votes

QGIS Apply Correction to Elevation Datum

Use this expression in the raster calculator: "name_of_your_dtm@1" + 2 But as Erik suggested it you shall have a look at the official tutorial where most of the solutions are already ...
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  • 1,416
0 votes
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PyQGIS script (.py) runs correctly on Windows but not on Mac

I found a solution, even if it doesn't solve all my doubts. The mac computer does not seem to recognise the relative path given, in any of the tried formulations (".\", ".", "....
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11 votes
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Update DEM based on line feature in QGIS

You can use r.carve within QGIS and set up a negative stream depth to increase the height of your DEM along your line feature (In the image below a positive stream depth have been applied to the DTM)
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1 vote

ArcGIS Online Interactive Legend filter features

To symbolize a feature based upon two TEXT fields create the symbology in ArcPro then share the layer to AGOL. Setting layer to unique values using two fields Results are:
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6 votes
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Deleting the same column(s) from different shapefiles in QGIS

A PyQGIS solution. Tested on QGIS 3.24.1-Tisler. Proceed with Plugins > Python Console > Show Editor and paste one of the scripts below. The press Run script and get the output. This approach ...
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3 votes

I don't see menu in QGIS Print Layout for enabling atlas, or browsing through atlas pages

In your Print Layout, go to 'View', then 'Toolbars' and check 'Atlas Toolbar' This is avaible for me in 3.10.2 so it should be in 3.10.4 aswell
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1 vote

Artificially extend a DEM to clip it

I found a way to do it on Python: (PS: I USED A DIFFERENT DEM FOR THE EXAMPLE, TO DEMONSTRATE HOW TO DEAL WITH BORDERS) # Open the DEM and extract all the info about it src = rio.open('IfSAR_merged....
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  • 107
0 votes
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Reprojecting from EPSG:3857 to EPSG:28992

I managed to solve the problem by converting from EPSG:4326 instead of from EPSG:3857. My understanding is that EPSG:4326 is a "flattened/map" version of EPSG:3857, so they are equivalent.
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QField - Can't locate project folder

The file is stored in a location only visible from a PC using a cable connection. Connect to your phone (I assume it is android) by cable and look here: Android\data\ch.opengis.qfield\files' It might ...
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