Core Concepts

What RTSeg Returns

RTSeg(trace) produces:

• offsets: list[tuple[int, int]] — character offsets into the trace
• labels: list[str] — one label per segment

You can reconstruct segments via:

segments = [trace[s:e] for (s, e) in offsets]

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Segmentation Base Unit (seg_base_unit)

Most engines operate on a base segmentation first:

• "clause" (default) → finer granularity
• "sent" → coarser segmentation

Quickstart — Single Engine

from rt_seg import RTSeg
from rt_seg import RTRuleRegex

trace = "First step... Then second step... Finally conclude."

segmentor = RTSeg(
    engines=RTRuleRegex,
    seg_base_unit="clause",
)

offsets, labels = segmentor(trace)

for (s, e), label in zip(offsets, labels):
    print(label, "=>", trace[s:e])

Multiple Engines + Late Fusion

If you pass multiple engines, you must provide an aligner.

from rt_seg import RTSeg
from rt_seg import RTRuleRegex
from rt_seg import RTBERTopicSegmentation
from rt_seg import OffsetFusionGraph

segmentor = RTSeg(
    engines=[RTRuleRegex, RTBERTopicSegmentation],
    aligner=OffsetFusionGraph,
    label_fusion_type="concat",  # or "majority"
    seg_base_unit="clause",
)
trace = "..."
offsets, labels = segmentor(trace)

Label Fusion Modes

• "majority" — choose most frequent label
• "concat" — concatenate labels (useful for debugging)