zero_crossing_rate — ONED signal op

• Data kinds: signal → measurement

• Call: import fullseye as fs; fs.ledger.zero_crossing_rate(x) (to call the implementation directly, import dsp; dsp.zero_crossing_rate(x); from the registry, ops1d.get("zero_crossing_rate"))

Usage

Fraction of adjacent samples that change sign — a cheap pitch/noisiness cue.

Exact zeros are neither a crossing nor a sign: a crossing is counted only when

the sign changes between consecutive *non-zero* samples, and the rate divides

by the number of adjacent sample pairs `len(x) - 1. So [1, 0, 1, 0, 1]` is

`0.0 and [1, 0, -1] is 0.5 (before 2026-09-02 diff(sign(x))` counted

every touch of zero as a crossing: `1.0` for both).

References (sample data, literature)

• Sample-data catalog (download URLs / licences) — 2-D uses skimage.data (BSD/public domain) plus synthetic images; 3-D lists download URLs for real data sources (Stanford, PDS, …).

• Operator provenance and references — the sources of the research/methods this op family came from.

• The canonical algorithm (author, year) and its uses are named in the family usage guide above.

Runnable examples (verified samples that actually call this op)

• (none yet)

Ops the type connects to (they accept measurement as input)

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Same category (signal)

lowpass · highpass · bandpass · envelope · rms · local_std · quantize · companding_mu_law

*Provenance: dsp.py — ONED operator registry. This per-op note is generated by tools/opdocs.py md (do not hand-edit).*

© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.