Questions tagged [field-calculator]
allows you to perform calculations on the basis of existing attribute values or defined functions in QGIS, ArcGIS, etc.
2,550 questions
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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 ...
- 51
1
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1
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62
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Finding the nearest line from point and writing the line’s end-vertex names into the point’s attributes in QGIS Field Calculator [closed]
I’m working in QGIS with three layers:
lines (LINESTRING)
test (POINT) — contains the point test1
vertices (POINT) — stores the line vertices, each with a name/ID field
For each point in test (e.g., ...
- 19
2
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1
answer
137
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QGIS 3.22.16, Add one letter and row number in column
I am using QGIS 3.22.16. I try to add an ID column that will contain the letter C plus row number. I open the field calculator and type: 'C'@row_number. Unfortunately, it does not work. I wonder what ...
- 402
1
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1
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Discrepancy in polygon area calculation in QGIS
I’m working with a polygon vector file in QGIS containing over 30,000 individual features. I want to calculate the cumulative area of all these polygons. I’ve tried two different methods.
Using QGIS:
...
- 13
5
votes
0
answers
62
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Displaying help on arguments, that should be entered next in QGIS custom function
When typing the name of a function, a helper is displayed with the arguments that must be entered next.
How can I do this for a custom function?
- 321
2
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0
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71
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Creating different service areas from layer based on attributes/area in QGIS
I want to create different service areas from a single layer in QGIS, based on attributes. I'm analysing greenspace supply in different cities in Germany. At it's core, what I want is bigger ...
4
votes
1
answer
238
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Wrong coordinates in QGIS Field Calculator when comparing with Google Earth
I'm working on a set of points for which I need coordinates, in QGIS. I'm not an expert in GIS, so I already know I'm wrong with something that should not be so complicated.
I don't understand why all ...
2
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0
answers
37
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Is it possible to calculate Zonal Statistics directly for a specific layer, without creating a new layer?
I want to calculate multiple Zonal Statistics from multiple raster files for Polygons.
The Zonal Statistics Tool create a new layer each time I apply the Zonal Statistics Tool. Is it possible to ...
- 413
3
votes
1
answer
110
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Updating geometry using geom_from_WKT from integer attributes
I'm having an issue using the geom_from_WKT when within the Field Calculator
I have some attributes, "easting" and "northing' on a point layer, and I'd like to update the geometry of ...
- 3,870
4
votes
1
answer
252
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Field calculator in ArcGIS Pro
I'm migrating from ArcMap to ArcGIS Pro 3.4 and finding simple field calculations do not work. No explanation I can find seems to address this issue, likely because it is too simple to be considered ...
- 41
3
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1
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166
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Adding What3Words to many points in QGIS Attribute Table
I want to be able to add a column of What3words API to my attribute table of about 900 points, however, I'm looking to see if it's possible without having to pay for the API key. Would anyone know a ...
- 31
2
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0
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Tool "Rectangles, Ovals, Diamonds" produes smaller squares than anticipated in QGIS [duplicate]
I used the tool "Rectangles, Ovals, Diamonds" in a model to construct squares over points with the parameters:
buffer shape = 0 (rectangles)
width = 1000
height = 1000
rotation = 0
number ...
- 51
4
votes
3
answers
288
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Creating increments of set number with QGIS Expression
I'm using QGIS 3.40 and want to create a column starting at 900 and adding 20 for each new row, getting a response of 900, 920, 940, etc - How do I do this?
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3
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1
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Generating segment label for each vertex including ring closure with QGIS Expression
I'm working with a table in QGIS where each row represents a vertex of a polygon, with columns "vertex_index" and "vertex_part_ring". Each "vertex_part_ring" defines a ...
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3
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1
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143
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"Eval Error: Cannot convert value to boolean" in QGIS Expression
I've got a line layer shapefile with lots of values in two columns ("Verstoord" and "Beleid"). I'm trying to fill a third column ("Advies") with values based on the first ...
- 177