Using delta with events that need to be grouped by another parameter

[tomdee]

I have events that contain a counter of a number of packets sent. Each event applies only to a single port.

How do I graph the rate of packets sent per port?

I've tried using delta, but I can't work out how to do that per port.

[justinfranks]

delta is only really a comparison between 2 events.

Would something like this work?

| timechart packets by port