I am doing research on how planned improvements in urban green will likely affect biodiversity using QGIS. Each form of urban green has a list of so-called references species, species that are important for the health of that particular green space. I also have a list of the species that have been sighted in and around that area [see image, it's mostly in Dutch].
RefSpecies is copied from an Excel, the sightings have been extracted using the field calculator expression below, which extracts the name of the species that are within a polygon:
aggregate('NDFF_Centroids_5Km', 'concatenate_unique', "soort_ned",filter:=intersects($geometry,geometry(@parent)), concatenator:=',')
NDFF_Centroids_5Km refers to the flora and fauna sightings data,
soort_ned refers to the kind of species.
My aim is to create a new column with lists that only include those species that have been sighted and are also present in the list of references species. This could be either a list of the species' names or just a single number representing the amount of sighted species that are present in the list of reference species.
I am not an QGIS-expert, and I have never worked with lists or concatenations in QGIS. I have created a simplified version to show what I mean. The column I want to create is
I am hoping someone knows how to do this and I'm open to other suggestions, such as not using lists or concatenations.