sega

Segment Evaluation & Generation Application

Evaluate data quality conditions on detector channel data and produce IGWN XML segment files or publish directly to DQSegDB. SEGA is built on the SGN streaming pipeline framework and driven by declarative YAML configuration.

Resources

• Documentation
• Source Code
• Issue Tracker

Installation

pip install sega

Where to Start

• Tutorial -- New to SEGA? Write a config file and generate your first segments step by step.
• User Guide -- Configuration, condition types, data sources, output modes, and the CLI.
• API Reference -- API documentation.

Features

• Declarative YAML configuration with includes, defaults, and bulk expansion
• Per-sample threshold, range, and bitwise condition checks
• Aggregate statistics (mean, RMS) with trend detection
• Boolean condition logic with arbitrary nesting (all_of, any_of, not)
• Infix expression syntax for complex boolean conditions (a & !b | c)
• Multiple data sources: gravitational wave frames, Arrakis, or synthetic data
• Output to IGWN XML segment files or DQSegDB
• Dry-run mode for config validation

Quickstart

Write a configuration file

Create a file called config.yaml:

meta:
  ifo: H1
  subsystem: DQ

conditions:
  calibrated:
    operator: bits_set
    channel: H1:GDS-CALIB_STATE_VECTOR
    bits: [0, 6]

  low_noise:
    operator: below
    channel: H1:PEM-CS_ACC_BEAMTUBE_X_DQ
    threshold: 500.0

  science_ready:
    operator: boolean
    expr: "calibrated & low_noise"

segments:
  H1:DQ-SCIENCE_READY:
    condition: science_ready
    version: 1
    limit: 16
    comment: "Calibrated and low noise"

Run from frame files

sega --config config.yaml --source frames \
     --frames /path/to/H-H1_R-*.gwf \
     --start 1187000000 --end 1187001000

This evaluates the conditions over the specified time range and writes an XML segment file to the current directory.

Validate a config without running

sega --config config.yaml --source fake --dry-run

The --dry-run flag parses and validates the configuration, printing a summary table of conditions and output segments. Use -v to include the full segment listing.

Stream from Arrakis

sega --config config.yaml --source arrakis

Without --start and --end, SEGA streams live data continuously. Press Ctrl+C to stop.

Publish to DQSegDB

sega --config config.yaml --source arrakis \
     --output-mode dqsegdb \
     --segment-server https://segments.ligo.org

Boolean expressions

Boolean conditions support infix notation with & (AND), | (OR), and ! (NOT), with standard precedence:

conditions:
  calibrated:
    operator: bits_set
    channel: H1:GDS-CALIB_STATE_VECTOR
    bits: [0, 6]

  injecting:
    operator: bits_set
    channel: H1:GDS-CALIB_STATE_VECTOR
    bits: [5]

  low_noise:
    operator: below
    channel: H1:PEM-CS_ACC_BEAMTUBE_X_DQ
    threshold: 500.0

  analysis_ready:
    operator: boolean
    expr: "calibrated & !injecting & low_noise"

This is equivalent to the explicit form:

  analysis_ready:
    operator: boolean
    all_of:
      - calibrated
      - not: injecting
      - low_noise