I want to group and count features with the same code attribute value.
I can classify the data and enable feature count in the layer list but I cannot get counts in the attribute table.
[GIS] Grouping and counting attribute data in QGIS
aggregationattribute-tablecountfields-attributesqgis
Related Solutions
This expression will count the number of populated places for each country:
aggregate(layer:='ne_110m_populated_places',
aggregate:='count',
expression:=name,
filter:=contains(geometry(@parent), $geometry)
)
you can use the same expression to get the sum, just change the aggregate to 'sum' and the expression to the field name to summarize.
Try Aggregate:
This algorithm take a vector or table layer and aggregate features based on a group by expression. Features for which group by expression return the same value are grouped together. It is possible to group all source features together using constant value in group by parameter, example: NULL. It is also possible to group features using multiple fields using Array function, example: Array("Field1", "Field2"). Geometries (if present) are combined into one multipart geometry for each group.
Best Answer
With a "Virtual Layer" through
Layer > Add Layer > Add/Edit Virtual Layer.... you can now use SQL on any layer in QGIS, for example the airport shapefile from the QGIS sample data:To count the number of airports by USE type and compute the average elevation use:
The results are loaded as a new layer: