MINING OBJECT MOVEMENT PATTERNS
FROM TRAJECTORY DATA
Phan Nhat Hai
4th October, 2013
Supervisors Dr. Dino Ienco, Pr. Pascal Poncelet, Dr. Maguelonne Teisseire
BACKGROUND AND MOTIVATION
Nowadays, many electronic devices are used for real world applications GPS, sensor networks, mobile phone, …
« interesting » patterns for: movement pattern analysis, animal behavior, route
planning and vehicle control, location prediction, …
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- Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
SOME EXAMPLES
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Route Planning
Animal migration analysis
-Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
The world’s largest traffic jam in history (China)
SPATIO-TEMPORAL DATA (ST)
Represented as a list of points, located in space and time T=(x1,y1, t1), …, (xn, yn, tn) position in space at time ti
was (xi, yi)
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- Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
MINING SPATIO-TEMPORAL PATTERNS FROM TRAJECTORY DATA (1)
Frequent Patterns:Frequent followed paths:
Group pattern [6], Tralus [7], …
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Region (Cluster)[6] Y. Wang et. al. Data Knowl. Eng., June 2006.[7] J. G. Lee et. al. In ACM SIGMOD ’07.
- Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
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[1] Z.Li et. al. PVLDB 10.[2] P. Kalnis et. al. SSTD’05.[3] J. Gudmundsson et. al. ACM GIS’06.[4] H. Jeung et. al. VLDB 08.[5] F. Verhein. SDM’09.
MINING SPATIO-TEMPORAL PATTERNS FROM TRAJECTORY DATA (2)
Clustering:Group together similar trajectoriesFor each group produce a summary
Flock [3], convoy [4], moving cluster [2], swarm & closed swarm [1], k-Star [5]
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Region (Cluster)
- Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
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SWARM – CLOSED SWARM [1]
Swarm - groups of objects (O, T ): At least objects move together timestamps
Closed Swarm Swarm which cannot be enlarged
Algorithm ObjectGrowth
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[1] Z.Li et. al. Swarm: mining relaxed temporal moving object clusters. PVLDB 2010.
- Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
CONVOY [4]
Convoy - groups of objects (O, T ): At least objects move together consecutive timestamps
Algorithm CuTS*
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[4] H. Jeung et. al. Discovery of convoys in trajectory databases. PVLDB 2008.
- Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
MOTIVATIONS (1)
Motivations: Complexity? Are they enough? Informative patterns?
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dataInformative patterns
extract
- Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
MOTIVATIONS (2)
Proposed solution
data
- Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
Unifying
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OUTLINE
Background and Motivations
Unifying Framework
Gradual Trajectory
Mining Representative Movement Patterns
Conclusions and Perspectives
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CLUSTER MATRIX
Objects: transactions Clusters: items
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diaper
beer
diaperbeer
- Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
FREQUENT CLOSED ITEMSET FROM CLUSTER MATRIX
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Frequent Itemset
- Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
THE MAIN INTUITION (FOLLOWING…)
We are now able to extract itemsets corresponding to a set of clusters occurring over time
Not movement patterns yet!
What about properties on Itemsets?
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- Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
SWARM
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- Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
PROPERTIES
In the same way it is possible to define properties for: Swarm, Closed Swarm, Convoy, Moving Cluster, Periodic Pattern, …
We are now able to extract different movement patterns!
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- Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
THE MAIN PROCESS (GET_MOVE)
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- Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
INCREMENTAL GET_MOVE
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- Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
THE MAIN PROCESS
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- Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
CMC CuTS* ObjectGrowth Vg-Growth Incremental GeT_Move
Convoys X X X
Closed Swarms X X
Group Patterns X X
Moving Cluster X
EXPERIMENTAL RESULTS
Datasets:
Competitive algorithms:
#objects #timestamps
Swainsoni 43 4,425
Buffalo 165 3,000
Synthetic* 500 10,000
Synthetic 2 50,000 10,000
- Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
* http://iapg.jade-hs.de/personen/brinkhoff/generator/
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SWAINSONI
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- Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
UNIFYING FRAMEWORK – CONCLUSIONS
GeT_Move: a unifying movement pattern mining approach
Properties adapted to specific movement patterns Proofs of properties Theorem providing that all the patterns are found
Incremental GeT_Move A new approach for identifying the size of blocks
Fully nested block partition
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- Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
OUTLINE
Background and Motivations
Unifying Framework
Gradual Trajectory
Mining Representative Movement Patterns
Conclusions and Perspectives
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ONE OF CLOSED SWARMS …
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- Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
…GRADUAL TRAJECTORIES
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-Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
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A CONCRETE EXAMPLE
-Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
PATTERN DEFINITION
The objects still remain in the next cluster The number of objects is equal-increasing (resp. equal-
decreasing) At least a number of certain timestamps
non-consecutive
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- Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
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TIME RELAXED GRADUAL TRAJECTORIES
Timestamps can be: non-consecutive within a sliding time window
-Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
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t1 t2 t3 ………… t999 t1000
A
F
Sliding window
Too far away
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EXPERIMENTAL RESULTS
Synthetic data: 500 objects - 10,000 timestamps Reasonable scalability Low complexity
-Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
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GRADUAL TRAJECTORY - CONCLUSIONS
New kinds of trajectories: gradual trajectory
ClusterGrowth: an efficient algorithm to extract all gradual trajectories
Fuzzy closed swarm
Too many extracted patterns: DiCompoGP algorithm to directly extract the top-k gradual
trajectories
Convergent Divergent
OUTLINE
Background and Motivations
Unifying Framework
Gradual Trajectory
Mining Representative Movement Patterns
Conclusions and Perspectives
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Methodology A set of movement patterns (closed swarms, convoys,
gradual trajectories, etc.) Employ MDL (Minimum Description Length) schema to
select the most informative and less redundant pattern set
Compo Algorithm Rank and select the most representative patterns Allow different types of pattern in the final results Characterize data by the selected patterns
CONTRIBUTIONS
-Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
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MOTIVATIONS
data
Patterns
1) One kind of patterns is not enough to describe the data!
2) Overlapping!
-Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
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PROBLEM STATEMENT
Given a spatio-temporal DB Odb and a set of patterns F (extracted from Odb)
Discover the optimal dictionary P (subset of F) compresses the data best w.r.t. the given encoding schema
L(p): number of bits to encode the pattern p + extra bit to encode the type of pattern
L(Odb|P): number of bits to encode the dataset Odb given P
MDL approach: LP(Odb) = L(P) + L(Odb|P)
-Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
ENCODING EXAMPLE (I)
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-Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
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ENCODING EXAMPLE (II)
L(ODB|P) = 4 + 6 + 2 + 1 + 1 = 14 L(P) = 4 + 5 + 3 + 4 = 16LP(ODB) = 30
L(ODB|P) = 4 + 5 + 2 + 1 + 1 = 13L(P) = 4 + 5 = 9LP(ODB) = 22
-Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
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NAÏVE COMPO VS SMART COMPO
We design two different approaches:
Naive Compo (baseline) Work in a greedy way Given the actual P, for each candidate p’ recompress the data
with P U p’ Select the p’ that obtain the best performance
Smart Compo Compute the gain incrementally Avoid to recompress the whole data Directly compute Gain(p’,P) = L(Odb|P) - L(Odb|P U p’) without
compute L(Odb|P U p’)
-Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
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EXPERIMENTAL RESULTS
-Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
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REPRESENTATIVE PATTERN - CONCLUSIONS
Propose an encoding scheme allowing multi-overlapping movement patterns
Propose two algorithms Naïve Compo (greedy approach) Smart Compo (compute gain incrementally)
Experimental results show that the top-k representative patterns are well adapted to the data
OUTLINE
Background and Motivations
Unifying Framework
Gradual Trajectory
Mining Representative Movement Patterns
Conclusions and Perspectives
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OVERALL CONCLUSIONS (1)
Three step framework GeT_Move: a unifying movement pattern mining
approach Discovering novel patterns: Gradual trajectory + Fuzzy
closed swarm Mining representative movement patterns
-Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
data
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OVERALL CONCLUSIONS (2) DEMONSTRATION SYSTEM
Link: http://www.lirmm.fr/~phan/multimove.jsp
-Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
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OVERALL CONCLUSIONS (3) – OTHER APPLICATIONS
Mining trajectories on genes
Mining trajectories on tweets
-Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
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PERSPECTIVES (1)
Streaming GeT_Move Mining representative movement patterns from streaming
trajectory data
-Background and Motivations - Unifying Framework - Gradual Trajectory - Mining Representative Movement Patterns - Conclusions & Perspectives
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PERSPECTIVES (2)
Trajectory mining on remote sensing, spatial information on satellite image processing
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EXTRA WORK Mining multi-relational gradual patterns (with Prof. Donato
Malerba) Kendal’s tau Gradual support
Communication graph summarization (with Dr. Francesco Bonchi)
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PUBLICATIONS[1] P. N. Hai, D. Ienco, P. Poncelet, M. Teisseire. "Mining Representative Movement Patterns
through Compression". PAKDD 2013.
[2] A.Z.E. Aabidine, A. Sallaberry, S. Bringay, M. Fabregue, C. Lecellier, P. N. Hai, P. Poncelet. “Co2Vis: A Visual Analytics Tool for Mining Co-expressed And Co-regulated Genes Implied in HIV Infections”. IEEE BioVis 2013.
[3] P. N. Hai, D. Ienco, P. Poncelet, M. Teisseire. "Mining Fuzzy Moving Object Clusters". ADMA 2012.
[4] P. N. Hai, D. Ienco, P. Poncelet, M. Teisseire. "Mining Time Relaxed Gradual Moving Object Clusters". ACM GIS 2012.
[5] F. Bouillot, P. N. Hai, N. Béchet, S. Bringay, D. Ienco, S. Matwin, P. Poncelet, M. Roche, and M. Teisseire. "How to Extract Relevant Knowledge from Tweets?". ISIP 2012.
[6] P. N. Hai, P. Poncelet, M. Teisseire. "GET_MOVE: An Efficient and Unifying Spatio-Temporal Pattern Mining Algorithm for Moving Objects". IDA 2012.
[7] P. N. Hai, P. Poncelet, M. Teisseire. "An Efficient Spatio-Temporal Mining Approach to Really Know Who Travels with Whom!". BDA 2012. (selected as Best papers)
[8] P. N. Hai, D. Ienco, P. Poncelet, M. Teisseire. "Extracting Trajectories through an Efficient and Unifying Spatio-Temporal Patten Mining System". ECML-PKDD 2012.
[9] P. N. Hai, P. Poncelet, M. Teisseire. "MovingObjects: Combining Gradual Rules and Spatio-Temporal Patterns". IEEE ICSDM 2011.
[10] P. N. Hai, P. Poncelet, M. Teisseire. "An Efficient Spatio-Temporal Mining Approach to Really Know Who Travels with Whom!". ISI special issue, selected papers from BDA’12, 2013, to appear.