There was a recent question on my first Form Charts post regarding advanced conditions. Since it's not really documented I did some experimenting.
In the last example I used a simple report filter. Show the "All Incidents by Category" report where the incident location is equal to the current form's incident location. Using this form chart interface limits you to a direct field mapping (location = current.location).
If you require a more advanced condition such as an OR condition you'll have to jump over to the "Advanced condition extension".