I have a polygon and values of polygon is divided into four categories (showed in four colors in picture). Is it possible to calculate the area covered by each category. Like my values range from 0-5, 5-10, 10-15, 15-20. How much total area is covered by 1st category and how much area covered by second category and so on.
I am doing my analysis on QGIS.
You can use an expression such as this one to get the percent of total area for a category:
sum(area($geometry),"your category field") / aggregate(@layer,'sum',area($geometry)) * 100
aggregate() sums up the area of the entire layer and sum(*area*,*group_by*) gets the area for the current features category.
Or to get the total area of a specific category:
sum(area($geometry),filter:="your category field" = 'my category')
I guess from these two you can stitch the one together you prefer if its not already the one. At last note the difference between $area and area($geometry).
