def copy(self):
# copy dqn.
dqn_mt = self.dqn.copy()
learner = DeepQlearn(dqn_mt, self.gamma, self.l2_reg, self.lr, self.memory_size, self.minibatch_size, self.epsilon)
learner.experience = list(self.experience)
learner.exp_idx = self.exp_idx
learner.total_exp = self.total_exp
learner.last_state = self.last_state
learner.last_action = self.last_action
learner._compile_bp()
return learner
