Count only not empty fields

Hi Lutz,

if I remember right, 'Apply when' does not work with functions, see answer at https://openforis.support/questions/1301/table-type-entity-how-to-check-sum-of-attributes-in-a-column

This might work for entity 'tree':

count(tree[idm:not-blank(tree_height)])

But if you want that 0 is regarded as missing height value, then use this

count(tree[tree_height>0])

Regards, Lauri