how to simulate custom reinforcement learning agent?

I have define custom environment(include step.m and reste.m ), and defined ddpg agent for trainning. After finished learning, i have get the trained agent, how can i export the action sequence from the result agent? in the step.m file, i have define render_plot function to simulate current state. Can i get the action from trained agent and import it to step.m to simulate?

[Ben]

Well, in reinforcement learning toolbox pre-defined agent, we can use sim(env, agent) to get the simulation from the trained agent. But how to deal with the custom environment with self defined step.m and reset.m ?