GrammarViz 3.0 source code public repository. This code is released under GPL v.2.0.

For the detailed software description, please visit our demo site.

GrammarViz 3.0 is a software for time series exploratory analysis with GUI and CLI interfaces. The GUI enables interactive time series exploration workflow that allows for variable length recurrent and anomalous patterns discovery from time series [4]:

It is implemented in Java and is based on continuous signal discretization with SAX, Grammatical Inference with Sequitur and Re-Pair, and algorithmic (Kolmogorov) complexity.

In contrast with 2.0, GrammarViz 3.0 introduces an approach for the grammar rule pruning and the automated discretization parameters selection procedure based on the greedy grammar rule pruning and MDL -- by sampling a possible parameters space, it finds a parameters set which produces the most concise grammar describing the observed time series the best, which often is close to the optimal -- here concise and describing are based on other specific criteria.

This release modernizes the build and fixes a cluster of long-standing defects in the automated parameter-selection ("Guess parameters") workflow. Highlights:

• Builds on Java 21 against the aligned jMotif 2.0.0 libraries (jmotif-sax and jmotif-gi 2.0.0); CI runs on Java 21 and 25.
• The parameter guesser now honors your input. Previously the window/PAA/alphabet ranges, step sizes, and minimal-cover threshold typed into the guesser dialog were silently discarded, and the inclusive maximum of each range was never actually evaluated -- both are fixed, with input validation on the dialog.
• Coverage-aware selection. The guesser now picks the most concise parameter set whose pruned grammar meets your minimal rule-cover threshold, instead of ignoring coverage; if none qualify it falls back gracefully and tells you so.
• No more silent hangs. A degenerate range or sampling error used to leave the UI stuck on "Stop!" indefinitely; it now reports the problem and resets.
• RePair is the default grammar-induction algorithm (selectable in Options, alongside Sequitur).
• First unit-test coverage for the grammar reductor and the parameter selector (26 tests).

See CHANGELOG.md for the full list, including behavior changes for existing users.

It also implements the "Rule Density Curve" and "Rare Rule Anomaly (RRA)" algorithms for time series anomaly discovery [5], that significantly outperform HOT-SAX algorithm for time series discord discovery, which is current state of the art. In the table below, the algorithms performance is measured in the amount of calls to the distance function (less is better). The last column shows the RRA performance improvement over HOT-SAX:

[1] Lin, J., Keogh, E., Wei, L. and Lonardi, S., Experiencing SAX: a Novel Symbolic Representation of Time Series. DMKD Journal, 2007.

[2] Nevill-Manning, C.G., Witten, I.H., Identifying Hierarchical Structure in Sequences: A linear-time algorithm. arXiv:cs/9709102, 1997.

[3] Larsson, N. J., Moffat, A., Offline Dictionary-Based Compression, IEEE 88 (11): 1722–1732, doi:10.1109/5.892708, 2000.

[4] Pavel Senin, Jessica Lin, Xing Wang, Tim Oates, Sunil Gandhi, Arnold P. Boedihardjo, Crystal Chen, and Susan Frankenstein. 2018. GrammarViz 3.0: Interactive Discovery of Variable-Length Time Series Patterns. ACM Trans. Knowl. Discov. Data 12, 1, Article 10 (February 2018), 28 pages. DOI: https://doi.org/10.1145/3051126

[5] Senin, P., Lin, J., Wang, X., Oates, T., Gandhi, S., Boedihardjo, A.P., Chen, C., Frankenstein, S., Lerner, M., Time series anomaly discovery with grammar-based compression, The International Conference on Extending Database Technology, EDBT 15.

We use Maven and Java 21 to build an executable. The GitHub Actions CI tests the build on a matrix of Linux, Windows, and macOS across Java 21 and 25 -- check the builds by clicking the "Java CI with Maven" badge at the top of this README. Below is a build trace on Java 21:

$ java -version
openjdk version "21.0.11" 2026-04-21
OpenJDK Runtime Environment (build 21.0.11+10-1-24.04.2-Ubuntu)
OpenJDK 64-Bit Server VM (build 21.0.11+10-1-24.04.2-Ubuntu, mixed mode, sharing)

$ mvn -version
Apache Maven 3.8.7
Java version: 21.0.11, vendor: Ubuntu, runtime: /usr/lib/jvm/java-21-openjdk-amd64
Default locale: en_US, platform encoding: UTF-8

$ mvn package -Psingle
[INFO] Scanning for projects...
....

[INFO] -------------------------------------------------------
[INFO]  T E S T S
[INFO] -------------------------------------------------------
[INFO] Running net.seninp.grammarviz.view.TestGrammarReductor
[INFO] Running net.seninp.grammarviz.view.TestParamsSamplerSelection
[INFO] Running net.seninp.grammarviz.view.TestParamsSamplerGrid
[INFO] Running net.seninp.grammarviz.anomaly.TestRRAanomaly
[INFO] Running net.seninp.tinker.TestInterval
[INFO]
[INFO] Results:
[INFO]
[INFO] Tests run: 26, Failures: 0, Errors: 0, Skipped: 0
[INFO]
[INFO] --- jacoco-maven-plugin:0.8.13:report (report) @ grammarviz2 ---
[INFO] Analyzed bundle 'GrammarViz2' with 25 classes
[INFO]
[INFO] --- maven-assembly-plugin:3.3.0:single (make-assembly) @ grammarviz2 ---
[INFO] Building jar: target/grammarviz2-3.0.0.jar
[INFO] Building jar: target/grammarviz2-3.0.0-jar-with-dependencies.jar
[INFO] ------------------------------------------------------------------------
[INFO] BUILD SUCCESS
[INFO] ------------------------------------------------------------------------
[INFO] Total time:  11.205 s
[INFO] ------------------------------------------------------------------------

To run the GrammarViz 3.0 GUI use the net.seninp.grammarviz.GrammarVizGUI class, or run the self-contained jar from the command line: $ java -Xmx4g -jar target/grammarviz2-3.0.0-jar-with-dependencies.jar (here I have allocated a max of 4 GB of memory for GrammarViz).

By using CLI as discussed in these tutorials, it is possible to save the inferred grammar, motifs, and discords.