find_pulses

Builtin index · Signal processing

result = find_pulses(x, [level=], [hysteresis=0], [polarity="positive"])

Input: x, level, hysteresis, polarity · Output: result

What it is

x: a length-N real vector or Signal; level/hysteresis as for find_edges; polarity (optional string): "positive" (default) pairs each rising edge with the next falling one, "negative" the reverse.

Overloads

One call shape — this function is not overloaded.

Code	Input	Output	Description
`result = find_pulses(x, [level=], [hysteresis=0], [polarity="positive"])`	`x` vector or Signal`x`: a length-N real vector or `Signal`. `level` optional`level`/`hysteresis` as for `find_edges`. `hysteresis` optional (default `0`)`level`/`hysteresis` as for `find_edges`. `polarity` string, optional (default `"positive"`)`polarity` (optional string): `"positive"` (default) pairs each rising edge with the next falling one, `"negative"` the reverse.	`Model` —kind `"pulses"` `stops` vectorvectors of integer sample indices — `stops`, not `ends`, because `end` is a Qu keyword `widths` vector or Signala vector of times: seconds for a `Signal`, samples otherwise, measured between the interpolated crossings so that `mean(p.widths)` equals `pulse_width(x)` exactly `count` numbera number	Returns a `Model` (kind `"pulses"`) with fields `starts`, `stops` (vectors of integer sample indices — `stops`, not `ends`, because `end` is a Qu keyword), `widths` (a vector of times: seconds for a `Signal`, samples otherwise, measured between the interpolated crossings so that `mean(p.widths)` equals `pulse_width(x)` exactly), and `count` (a number). A partial pulse at either end of the record — already high when capture started, or still high when it stopped — has only one of its two edges and is not reported; its width is genuinely unknown.

Examples

No documentation example calls this form yet. The Signal processing chapter is where one belongs.

How it works

find_pulses(x, [level=], [hysteresis=], [polarity="positive"]) -- consecutive opposite-going edge pairs, as a Model with parallel fields starts, stops and widths, plus a scalar count. Field names are plural to match findpeaks's own peaks/locations/ prominences/widths convention; stops rather than the obvious ends because end is a Qu keyword and a field spelled that way would be awkward to reach. UNITS, because this record deliberately mixes them: starts/stops are integer sample INDICES (they index into x), while widths are TIMES -- seconds for a Signal, samples otherwise -- measured between the interpolated crossings. The alternative, widths in whole samples, would make mean(p.widths) disagree with pulse_width(x) on the same input, which is a worse trap than a documented mixed record. A partial pulse at either end of the record -- already high when capture started, or still high when it stopped -- has only one of its two edges and is NOT reported. Its width is genuinely unknown and a truncated one would look fine.

From the note above this builtin in the interpreter, where the reasoning was written down as it was built.