Adding unique ID for consecutive groups using Field calculator in QGIS

Question

I found a similar question on this site and the answer suggested:

array_find(
    array_distinct(
        array_agg("PortCluster_ID")
        ),
        "PortCluster_ID"
    ) + 1

but using this expression gives me the following result (group1)

What I want to do is have what I wrote in white color on the attached image. As you can see I have consecutive "PortCluster_ID"s ordered in time, and i have a group of 119, then a group of 111 and then a group of 119 again, for this second group of 119 I want to have a new "ID".

What this data represents is fishing trips in and out of ports, some trips end in the same port (same "PortCluster_ID") but are obviously a different trip (ordered in ascending time).

Answer 1

create an ID field following the GpsTime field, then create the group1 field and populate it with the following expression (can be improved):

with_variable('cucu',
   aggregate( 
   layer:=@layer_name,
   aggregate:='array_agg',
   expression:=
   (array_find(array_agg("ID", "PortCluster_ID"),"ID"))-"ID"),
with_variable('cucu2',
   (array_find(array_agg("ID", "PortCluster_ID"),"ID"))-"ID",
   array_find(array_distinct(@cucu),@cucu2)+1))

the scheme used:

sample data: https://gist.github.com/pigreco/48cf061c183809b0e69628a13493f771