Questions tagged [qgis-expression]
refers to a kind of dialect QGIS uses to expand its features, primarily used to calculate fields, manipulate geometry or manage symbology.
194 questions
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Return geometry values based on field in attribute table
I have several linestrings and want to place labels at varying positions along those lines. To not play around with additional (point) features, I need to return the x- and y-position along the ...
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Splitting polygons with line with Geometry generator, using QGIS expressions
The question
I QGIS, you can split polygons with lines using Split with lines algorithm. I want to do this in Geometry genrator, using QGIS expressions. However, there is no expression/function ...
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Creating new attribute with name of feature with the highest group value using QGIS Expression
In QGIS, I have a point layer. I'd like to create a new attribute that will retrieve the value from the "Name" field for the object that has the highest value in the "he" field in ...
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Expression Builder not allowing multiple expressions with "replace"
I am trying to use the expression label to make a couple simple changes to my labels. I am able to successfully change one using replace-- like so:
replace("columnname", 'oldname', 'newname')...
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Numbering QGIS fishnet from lower left, moving right
I create a fishnet in QGIS and want the FID numbering to start from the lower left corner and increase row-wise to the right. By default, the FID numbers start from the upper left and increase column-...
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Geometry generator skips Null values in QGIS
I have a geometry generator, which I have drastically simplified below, it's for drawing tree canopies.
I want to be able to expand this to 8 points (which is easy), but have the expression skip any ...
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Issue with OR operator in QGIS Rule-Based Labelling expression
I want to label only the major roads (primary, trunk, and tertiary) in the roads layer, using the "Highway" field. I have created a rule based expression:
"HIGHWAY"= 'primary' OR '...
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Combining replace and title function for labelling in QGIS Expression
I need to clean up the labels from a shapefile dataset for mapping. Working in QGIS.
Current values appear as DUNDAS RAILWAY STATION, TOWN HALL RAILWAY STATION, etc.
I need to strip the "RAILWAY ...
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HTML MapTip to show elevation data from DEM layer in QGIS
Is there a way to set the HTML MapTip to show elevation data on a DEM layer in QGIS?
The QGIS expression builder doesn't have any functionality to connect to mouse movement. I am guessing a custom ...
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Mapping X and Y Coordinates with Geometry By Expression in QGIS
I have a csv file, containing the x and y coordinates (EPSG:2229) of 4 points:
I would like to use the Geometry By Expression tool in QGIS to map these points. The expression at the very basic level ...
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Smoothing curves with specific radius in QGIS
I did not find a good solution to this problem by searching this page (and the rest of the web) so here we go, even if it sounds trivial:
I have a project in QGIS where I have do draw an access route ...
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Select by Expression no longer working as before in QGIS
I have a vector layer of contours with a 0.25m elevation difference. These are standard vector contours generated by the QGIS Contour... tool, with the elevation value stored in column ELEV. For a ...
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QGIS Raster Calculator Expression Box Text Font Very Small
Does anyone know how to increase the font size in the QGIS Raster Calculator Expression box as its very small
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Simplifying defining several variables at once with QGIS Expression
Using QGIS expressions, I want to define several variables. For this, there is the function with_variable(). However, you can just define one variable at once, and the expression has to be repeated ...
- 80.2k
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Getting attribute value on intersection with QGIS Expression
I am using QGIS 3.34 and i want to get an attribute value in a field calculator expression using intersection. My layers are a polygon layer with some attribute, and a point layer.
I need that when i ...
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