On 17/08/17 22:41, Christine wrote: > if you want to get a density of school points in each polygon, you may > calculate this in the field calculator. > Assure, you are working in a projected coordinate sytem. Open attribute > table and choose 'open field calculator'. With the field calculator dialog > open, give a name to a new attribute for school density, choose an > appropriate output field type (probably decimal number, real), output field > length and precision and use an expression pattern like > <name of attribute of points count> / $area
Thanks Christine! That solved my problem too :-) I have 136 polygons, or rather city sub-areas, with data on different kinds of densities (e.g. density of schools, density of churches and density of pizzerias). I would like to create a field with the field calculator, for each kind of density, that preserves the order of the polygons: the sub-area with the most pizzerias per square meter gets number one, the second densest sub-area the number two, etc... There should be a smarter way to do that then manually sorting a density field column, then create a new "density order"-field, and then typing in 1, 2, 3, ... , 134, 135, 136 from the top to the bottom (and then repeat that procedure for each kind of density!). Grateful for advice! Best regards. //Erik
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