signal op• 数据种类:positions → table
• 调用: import fullseye as fs; fs.ledger.point_spectrum(positions, extent=None, n_freq=2048, f_max=None, method='direct', weights=None, bins_per_period=8)(要直接调用实现,import dsp; dsp.point_spectrum(positions, extent=None, n_freq=2048, f_max=None, method='direct', weights=None, bins_per_period=8);从台账取用则 ops1d.get("point_spectrum"))
> 该算子的说明尚无译文,以下照原文给出。
Periodogram of event positions — defects, impacts, counts, arrivals.
:func:spectrum needs an evenly sampled signal, but a great deal of
industrial data arrives as a *list of positions*: where each defect was on
the web, when each particle was counted, at what angle each dent sits. The
usual workaround is to histogram the positions and FFT the histogram, which
works but hides two choices — bin width and record length — that decide the
answer. This operator makes both explicit and returns them.
*method* picks the estimator:
`"direct"`
the point-process (Bartlett) periodogram
`|sum_j w_j exp(-2 pi i f x_j) - rate * integral|^2 / sum_j w_j`,
evaluated at each requested frequency. No binning at all, so no bin
width to choose and no aliasing from one. The subtracted term is the
contribution a *uniform* process of the same rate would make; without it
every spectrum peaks at f -> 0 simply because events exist.
`"binned"`
histogram the positions, then `rfft`, with the bin width set so the
finest frequency asked for still gets `bins_per_period` samples per
cycle. Cheaper for very many events, and the result is what a
histogram-and-FFT pipeline would have produced.
The frequency resolution is a property of the record, not of the method.
Two periods closer than `1/extent` apart cannot be told apart by either
estimator, and the returned dict says so in `resolution`: read it before
reading a peak, not after.
A periodic train of events is a comb, not a line. Its harmonics at
`k/period are as tall as the fundamental, so argmax` of this spectrum
routinely returns `period/k` rather than the period. Measured on 93 events
(43 spaced 471.24 apart with 1.5 of jitter, plus 50 uniformly random) over a
record of 20000: the global maximum lands on `58.90 with direct` (the
8th harmonic) and `52.35 with binned` (the 9th), while the fundamental
is present and prominent in both — `direct` puts 0.947 of the maximum
power at `1/471.24, binned` 0.379. Take the lowest frequency whose
first few harmonics *all* stand, rather than the tallest line — see
`examples/poc_web_roll_periodicity.py`, which is what this operator was
added for.
Returns a dict: `freq (cycles per unit of *positions*), power`,
`resolution (1/extent), extent, n_events, method`, and
`bin_width (None for "direct"`).
Fail-closed: fewer than two events raises `ValueError` — a periodogram of
one point is not a weak measurement, it is not a measurement.
• 示例数据目录(下载 URL / 许可证) —— 2-D 用 skimage.data(BSD/公有领域)加合成图,3-D 给出真实数据源(Stanford/PDS 等)的下载 URL。
• 算子来历与参考文献 —— 该算子族所依据的研究/方法出处。
• 算法的正典(作者・年份)与用途见上面的族使用指南。
• poc_web_roll_periodicity — py -3.11 examples/poc_web_roll_periodicity.py
table 作为输入)—
signal)lowpass · highpass · bandpass · envelope · rms · local_std · quantize · companding_mu_law
*Provenance: dsp.py — ONED 算子登记表。本条目由 tools/opdocs.py md 自动生成(请勿手工编辑)。*
© 2026 Kazufumi Furuse — Fullseye operator documentation. Licensed under Apache-2.0.