5e76b6981d0b48def00d4fa97caec24accf402fd,contents/5.2_Prioritized_Replay_DQN/RL_brain.py,SumTree,get_leaf,#SumTree#,59

Before Change

    def get_leaf(self, lower_bound):
        leaf_idx = self._retrieve(lower_bound)  // search the max leaf priority based on the lower_bound
        data_idx = leaf_idx - self.capacity + 1
        return [leaf_idx, self.tree[leaf_idx], self.data[data_idx]]

    def _retrieve(self, lower_bound, parent_idx=0):
        
        Tree structure and array storage:

After Change

        while True:     // the while loop is faster than the method in the reference code
            cl_idx = 2 * parent_idx + 1         // this leaf"s left and right kids
            cr_idx = cl_idx + 1
            if cl_idx >= len(self.tree):        // reach bottom, end search
                leaf_idx = parent_idx
                break
            else:       // downward search, always search for a higher priority node
                if v <= self.tree[cl_idx]:
                    parent_idx = cl_idx
                else:
                    v -= self.tree[cl_idx]
                    parent_idx = cr_idx

        data_idx = leaf_idx - self.capacity + 1
        return leaf_idx, self.tree[leaf_idx], self.data[data_idx]

    @property

Instances