Question How can I model multiple dynamic targets?

I have an AI character that will collect coins on the screen. I assume AI character will see what the player sees on the screen, so coin number will change. When there is a single coin, I can create an observation vector and set position to it. How can I model multiple dynamic targets?

 

you want a buffer sensor if the number of observations needs to be dynamic
https://docs.unity3d.com/Packages/c.../api/Unity.MLAgents.Sensors.BufferSensor.html
basically allows you to assign a vector observation via code