Hi there everyone.
First of all thanks for helping, and I realize I need some tutorials in python and can hopefully address that soon.
Problem: Using the Calculate Field tool I would like copy values from two other fields based on specific criteria. For instance I have a new field called "UnathorizedOccupantID". I would like to copy values from the field called "ClusterID", however when there is a value of -1 I would like to copy the corresponding values from the "SourceID" field. As seen here:

I believe this will get me to the next part of the analysis which is aggregating the cluster ID's using the Dissolve tool.
Thanks for any help it is greatly appreciated!