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AutoPlait: Automatic Mining of Co-evolving Time Sequences Yasuko Matsubara (Kumamoto University) Yasushi Sakurai (Kumamoto University) Christos Faloutsos (CMU) SIGMOD 2014Y. Matsubara et al.1
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Time Motivation Given: co-evolving time-series – e.g., MoCap (leg/arm sensors) “Chicken dance” Y. Matsubara et al.2SIGMOD 2014
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Time Motivation Given: co-evolving time-series – e.g., MoCap (leg/arm sensors) “Chicken dance” Y. Matsubara et al.3SIGMOD 2014 Q. Any distinct patterns? Q. If yes, how many? Q. What kind?
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Motivation Challenges: co-evolving sequences – Unknown # of patterns (e.g., beaks) – Different durations Y. Matsubara et al.4SIGMOD 2014 Time …
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Motivation Challenges: co-evolving sequences – Unknown # of patterns (e.g., beaks) – Different durations Y. Matsubara et al.5SIGMOD 2014 Time … Q. Can we summarize it automatically ?
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Motivation Goal: find patterns that agree with human intuition Y. Matsubara et al.6SIGMOD 2014 Time
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Motivation Goal: find patterns that agree with human intuition Y. Matsubara et al.7SIGMOD 2014 AutoPlait: “fully-automatic” mining algorithm
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Importance of “fully-automatic” No magic numbers!... because, Big data mining: -> we cannot afford human intervention!! Y. Matsubara et al.8SIGMOD 2014 Manual -sensitive to the parameter tuning -long tuning steps (hours, days, …) Automatic (no magic numbers) - no expert tuning required
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Outline SIGMOD 20149 -Motivation -Problem definition -Compression & summarization -Algorithms -Experiments -AutoPlait at work -Conclusions Y. Matsubara et al.
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Problem definition SIGMOD 201410Y. Matsubara et al. Key concepts -Bundle: -Segment: -Regime: -Segment-membership: given hidden
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Problem definition SIGMOD 201411Y. Matsubara et al. Bundle : set of d co-evolving sequences Bundle X (d=4) given
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Problem definition SIGMOD 201412Y. Matsubara et al. Segment: convert X -> m segments, S Segment (m=8) s1s2 s3s4 s5s6 s7 s8 hidden
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Problem definition SIGMOD 201413Y. Matsubara et al. Regime: segment groups: : model of regime r Regimes (r=4) wings beaks hidden
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Problem definition SIGMOD 201414Y. Matsubara et al. Segment-membership: assignment Segment- membership (m=8) F = { 2, 4, 1, 3, 2, 4, 1, 3 } hidden
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Problem definition SIGMOD 201415 Given: bundle X Y. Matsubara et al.
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Problem definition SIGMOD 201416 Given: bundle X Find: compact description C of X Y. Matsubara et al.
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Problem definition SIGMOD 201417 Given: bundle X Find: compact description C of X Y. Matsubara et al. m segments r regimes Segment-membership
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Outline SIGMOD 201418 -Motivation -Problem definition -Compression & summarization -Algorithms -Experiments -AutoPlait at work -Conclusions Y. Matsubara et al.
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Main ideas Goal: compact description of X without user intervention!! Challenges: Q1. How to generate ‘informative’ regimes ? Q2. How to decide # of regimes/segments ? SIGMOD 2014Y. Matsubara et al.19
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Main ideas Goal: compact description of X without user intervention!! Challenges: Q1. How to generate ‘informative’ regimes ? Idea (1): Multi-level chain model Q2. How to decide # of regimes/segments ? Idea (2): Model description cost SIGMOD 2014Y. Matsubara et al.20
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SIGMOD 201421 Idea (1): MLCM: multi-level chain model Q1. How to generate ‘informative’ regimes ? Y. Matsubara et al. Model SequencesRegimes beaks claps wings
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SIGMOD 201422 Idea (1): MLCM: multi-level chain model Q1. How to generate ‘informative’ regimes ? Idea (1): Multi-level chain model – HMM-based probabilistic model – with “across-regime” transitions Y. Matsubara et al. beaks wings claps Model SequencesRegimes
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Idea (1): MLCM: multi-level chain model SIGMOD 2014Y. Matsubara et al.23 r regimes (HMMs) across-regime transition prob. Single HMM parameters Details
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Idea (1): MLCM: multi-level chain model SIGMOD 2014Y. Matsubara et al.24 Regimes r=2 Regime 1 (k=3) Regime 2 (k=2) r regimes (HMMs) across-regime transition prob. Single HMM parameters state 1 state 3 state 2 state 1 state 2 Regime switch Regime1 “beaks” Regime2 “wings” Details
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SIGMOD 201425 Idea (2): model description cost Q2. How to decide # of regimes/segments ? Idea (2): Model description cost Minimize coding cost find “optimal” # of segments/regimes Y. Matsubara et al.
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Idea (2): model description cost Idea: Minimize encoding cost! SIGMOD 2014Y. Matsubara et al.26 Good compression Good description (# of r, m) Cost M (M) + Cost c (X|M) Model cost Coding cost min ( )
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Idea (2): model description cost Total cost of bundle X, given C SIGMOD 2014Y. Matsubara et al.27 Details
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Idea (2): model description cost Total cost of bundle X, given C SIGMOD 2014Y. Matsubara et al.28 Model description cost of Θ Coding cost of X given Θ # of segments/regim es segment lengths segment- membership F duration/dimensi ons Details
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Outline SIGMOD 201429 -Motivation -Problem definition -Compression & summarization -Algorithms -Experiments -AutoPlait at work -Conclusions Y. Matsubara et al.
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AutoPlait Overview SIGMOD 2014Y. Matsubara et al.30 Iteration 0 r=1, m=1 Start! 1 2 3 4 5 6 7 Iteration 0 1 2 3 4 5 6 7 Iteration r=1
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AutoPlait Overview SIGMOD 2014Y. Matsubara et al.31 Iteration 1 r=2, m=4 0 1 2 3 4 5 6 7 Iteration r=1 r=2 Split
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AutoPlait Overview SIGMOD 2014Y. Matsubara et al.32 Iteration 1 r=2, m=4 Iteration 2 r=3, m=6 Split 0 1 2 3 4 5 6 7 Iteration r=1 r=2 r=3
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AutoPlait Overview SIGMOD 2014Y. Matsubara et al.33 Iteration 1 r=2, m=4 Iteration 2 r=3, m=6 Iteration 4 r=4, m=8 Split 1 2 3 4 5 6 7 Iteration 0 1 2 3 4 5 6 7 Iteration r=1 r=2 r=3 r=4
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AutoPlait Algorithms 1.CutPointSearch Find good cut-points/segments 2.RegimeSplit Estimate good regime parameters Θ 3.AutoPlait Search for the best number of regimes (r=2,3,4…) SIGMOD 2014Y. Matsubara et al.34 Inner-most loop Inner loop Outer loop
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1.CutPointSearch Given: - bundle - parameters of two regimes Find: cut-points of segment sets S 1, S 2, SIGMOD 2014Y. Matsubara et al.35 Inner-most loop
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1.CutPointSearch SIGMOD 2014Y. Matsubara et al.36 state 1 state 2 state 3 state 2 state 1 switch?? Inner-most loop DP algorithm to compute likelihood: Details
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1.CutPointSearch Theoretical analysis Scalability - It takes time (only single scan) - n: length of X - d: dimension of X - k: # of hidden states in regime Accuracy It guarantees the optimal cut points - (Details in paper) SIGMOD 2014Y. Matsubara et al.37 Inner-most loop Details
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2.RegimeSplit Given: - bundle Find: two regimes 1. find cut-points of segment sets: S 1, S 2 2. estimate parameters of two regimes: SIGMOD 2014Y. Matsubara et al.38 Inner loop
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2.RegimeSplit Two-phase iterative approach -Phase 1: (CutPointSearch) -Split segments into two groups : -Phase 2: (BaumWelch) -Update model parameters: SIGMOD 2014Y. Matsubara et al.39 Phase 1 Phase 2 Inner loop Details
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3.AutoPlait Given: - bundle Find: r regimes (r=2, 3, 4, … ) - i.e., find full parameter set SIGMOD 2014Y. Matsubara et al.40 Outer loop
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3.AutoPlait Split regimes r=2,3,…, as long as cost keeps decreasing - Find appropriate # of regimes SIGMOD 2014Y. Matsubara et al.41 Outer loop
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3.AutoPlait Split regimes r=2,3,…, as long as cost keeps decreasing - Find appropriate # of regimes SIGMOD 2014Y. Matsubara et al.42 r=2, m=4 r=3, m=6 r=4, m=8 Outer loop
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Outline SIGMOD 201443 -Motivation -Problem definition -Compression & summarization -Algorithms -Experiments -AutoPlait at work -Conclusions Y. Matsubara et al.
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Experiments We answer the following questions… Q1. Sense-making Can it help us understand the given bundles? Q2. Accuracy How well does it find cut-points and regimes? Q3. Scalability How does it scale in terms of computational time? SIGMOD 201444Y. Matsubara et al.
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Q1. Sense-making MoCap data SIGMOD 201445Y. Matsubara et al. AutoPlait (NO magic numbers) DynaMMo (Li et al., KDD’09) pHMM (Wang et al., SIGMOD’11)
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Q1. Sense-making MoCap data SIGMOD 201446Y. Matsubara et al. AutoPlait (NO magic numbers)
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Q2. Accuracy (a) Segmentation (b) Clustering SIGMOD 201447Y. Matsubara et al. AutoPlait needs “no magic numbers” Target
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Q3. Scalability Wall clock time vs. data size (length) : n SIGMOD 201448Y. Matsubara et al. AutoPlait scales linearly, i.e., O(n) AutoPlait DynaMMo pHMM
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Outline SIGMOD 201449 -Motivation -Problem definition -Compression & summarization -Algorithms -Experiments -AutoPlait at work -Conclusions Y. Matsubara et al.
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AutoPlait at work AutoPlait is capable of various applications, e.g., App1. Model analysis - Web-click sequences App2. Event discovery - Google Trend data SIGMOD 201450Y. Matsubara et al.
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AutoPlait at work AutoPlait is capable of various applications, e.g., App1. Model analysis - Web-click sequences App2. Event discovery - Google Trend data SIGMOD 201451Y. Matsubara et al.
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App1. Model analysis (WebClick) Web-click sequences (1 month, 5urls) – 5urls: blog, news, dictionary, Q&A, mail – every 10 minutes SIGMOD 201452Y. Matsubara et al. Time (per 10 minutes)
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App1. Model analysis (WebClick) Web-click sequences (1 month, 5urls) SIGMOD 201453Y. Matsubara et al. AutoPlait finds 2 patterns: weekday/weekend !
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App1. Model analysis (WebClick) Web-click sequences (1 month, 5urls) SIGMOD 201454Y. Matsubara et al. AutoPlait finds 2 patterns: weekday/weekend ! Monday (but holiday)
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App1. Model analysis (WebClick) Pattern of weekday regime SIGMOD 201455Y. Matsubara et al. Observation: Working hard every weekday (i.e., using dictionary, news sites) Details
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App1. Model analysis (WebClick) Pattern of weekend regime SIGMOD 201456Y. Matsubara et al. Observation: No more work on weekend (i.e., blog, mail, Q&A for non-business purposes) Details
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AutoPlait at work AutoPlait is capable of various applications, e.g., App1. Model analysis - Web-click sequences App2. Event discovery - Google Trend data SIGMOD 201457Y. Matsubara et al.
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App2. Event discovery (GoogleTrend) Anomaly detection (flu-related topics,10 years) SIGMOD 201458Y. Matsubara et al.
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App2. Event discovery (GoogleTrend) Anomaly detection (flu-related topics,10 years) SIGMOD 201459Y. Matsubara et al. AutoPlait detects 1 unusual spike in 2009 (i.e., swine flu)
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App2. Event discovery (GoogleTrend) Turning point detection (seasonal sweets topics) SIGMOD 201460Y. Matsubara et al.
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App2. Event discovery (GoogleTrend) Turning point detection (seasonal sweets topics) SIGMOD 201461Y. Matsubara et al. Trend suddenly changed in 2010 (release of android OS “Ginger bread”, “Ice Cream Sandwich”)
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App2. Event discovery (GoogleTrend) Trend discovery (game-related topics) SIGMOD 201462Y. Matsubara et al.
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App2. Event discovery (GoogleTrend) Trend discovery (game-related topics) SIGMOD 201463Y. Matsubara et al. It discovers 3 phases of “game console war” (Xbox&PlayStation/Wii/Mobile social games)
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Outline SIGMOD 201464 -Motivation -Problem definition -Compression & summarization -Algorithms -Experiments -AutoPlait at work -Conclusions Y. Matsubara et al.
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Conclusions AutoPlait has the following properties Effective Find optimal segments/regimes Sense-making Reasonable regimes Fully-automatic No magic numbers Scalable It scales linearly SIGMOD 2014Y. Matsubara et al.65 ✔ ✔ ✔ ✔
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Thank you! SIGMOD 201466Y. Matsubara et al. Code: http://www.cs.kumamoto-u.ac.jp/~yasuko/software.html Mail: yasuko@cs.kumamoto-u.ac.jp
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