Travel Trajectory Frequent Pattern Mining Based on Differential Privacy Protection

Algorithm 2

Trajectory graph frequency calculation (TGFC).

Input: Graph Database , Canonical Code of Trajectory Subgraph , the number of edges with as the node

Output: the number of trajectory subgraph in graph database

1. , trajectory subgraph ,

2. According to the definition of , has the largest node degree, and takes the node with the highest degree as the starting match query point.

3. Each time, select the node with the highest degree from for matching. Update to .

4. for each node in :

5.  if & &: / /

6.   

7. end for

8. for each node in :

9.  

10. end for

11. return num

12. -------Subgraph Isomorphism Search,------13. if:

14.   num+=1

15. return num

16. else if

17. if is the last node of :

18.  num +=1

19. return num

20. for each unvisited node in :

21.   if & &:

22.    traversing all the remaining isomorphism points, obtained isomorphism subgraph by the adjacency matrix.

23.    num+= :

24.   else

25.   :

26. end for

27. return num