I have two CSV data sets. The first on is monthly data or a certain variable(PM_2.5) given by spacial constrains (latitude and longitude) which can be seen as the place variables. The second data frame contains different start and end dates for the observation. Also, those are given under the same spacial constraint and for each individual v1. You can see the data structure in the pictures. enter image description here enter image description here
I want to sum all observations of (PM_2.5) for one individual (ID) over the observation period (start date to end date) given the constraint that the geospatial identification (latitude, longitude) is the same.
Thanks a lot for your help. Best, Luise