Projection Bands

Install and import#

npm install fintech-algorithms

import { projectionBands } from "fintech-algorithms/technical-indicators/bands-envelopes-and-squeezes/projection-bands";

Signature#

projectionBands(input)

Projection Bands: fits a least-squares slope to the highs and to the lows of the last period bars, projects every bar in the window forward along that slope, and takes the highest projected high and the lowest projected low.

Parameters#

Returns#

TopicResult

series holds only upper and lower -- this topic emits no center -- and latest carries the last of each. Both share a warm-up of period - 1 leading nulls, so ready_at is 19 at the default period.

Warm-up#

The first `period - 1` bars (19 at the default period) positions are null. Each band is recomputed from a full window of highs or lows; there is no partial-window output and no carry forward between windows.

Errors#

• When parameters.period is not an integer >= 2 — throws Error
• When a bar is missing open, high, low, close, or volume, or one of them is not a finite number — throws Error
• When bars are not strictly ordered by timestamp, or a bar's high is below its open, low, or close — throws Error

Complexity: time O(n * period), space O(n).

Worked example#

executed Captured by running this function on the input its own test provides. Real output of real code — but not asserted against a published figure.

Input#

{
  "bars": [
    {
      "timestamp": "2024-01-02",
      "basis": "synthetic-unadjusted",
      "open": 100,
      "high": 101.45,
      "low": 98.695,
      "close": 100,
      "volume": 750000,
      "benchmark": 200
    },
    {
      "timestamp": "2024-01-03",
      "basis": "synthetic-unadjusted",
      "open": 101.49111452,
      "high": 103.38381693,
      "low": 100.05480022,
      "close": 101.78791214,
      "volume": 795117,
      "benchmark": 200.56326135
    },
    {
      "timestamp": "2024-01-04",
      "basis": "synthetic-unadjusted",
      "open": 102.45519048,
      "high": 104.6701838,
      "low": 100.91147007,
      "close": 102.9549389,
      "volume": 840234,
      "benchmark": 201.11020913
    }
  ],
  "parameters": {}
}

Call#

projectionBands(input)

Returns#

object with 9 fields: topic_id, title, state, ready, ready_at, series, latest, parameters, …

{
  "topic_id": "D07-F07-A09",
  "title": "Projection Bands",
  "state": "calculated",
  "ready": true,
  "ready_at": 19,
  "series": {
    "upper": [null, null, null, null, null, null],
    "lower": [null, null, null, null, null, null]
  },
  "latest": {
    "upper": 109.63429948293232,
    "lower": 98.68874251
  },
  "parameters": {},
  "diagnostics": {
    "causal": true,
    "input_count": 96
  }
}

Diagrams#

Calculation flow#

flowchart LR
    A["ordered OHLC or close observations, a declared centerline,"] --> B["Validate order, basis, and finite values"]
    B --> C["Apply the selected Projection Bands convention"]
    C --> D["Emit value, readiness, and diagnostics"]
    D --> E["Interpret descriptively; test outcomes separately"]
    B -->|invalid or insufficient| X["Withhold output with a reason"]

stateDiagram-v2
    [*] --> Waiting
    Waiting --> Ready: enough valid causal observations
    Waiting --> Rejected: malformed or unsupported input
    Ready --> Calculated: selected formula applied
    Calculated --> Interpreted: diagnostic and limitation retained
    Interpreted --> Ready: next observation arrives
    Rejected --> Waiting: corrected input and deterministic reset

How it works#

This page states the contract — how to call it correctly. The article explains the concept: why it works, and where it breaks.

Read the article →

References#

• TA-Lib function groups — see linked primary or authoritative record
• TA-Lib C/C++ API — see linked primary or authoritative record
• TA-Lib maintained source — see linked primary or authoritative record
• Evidence decision
• Level 1 evidence map

The rest of the Bands, Envelopes, and Squeezes family#

• Bollinger %BBollinger Bands together with %B, the close's position between the lower and upper band.
• Moving Average EnvelopeMoving Average Envelope: a simple moving average of close with bands set a fixed percentage above and below it.
• ATR BandsATR Bands: a simple moving average of close with bands multiplier Average True Ranges above and below it.
• Standard Deviation ChannelStandard Deviation Channel: a simple moving average of close with bands multiplier population standard deviations above and b…
• Regression ChannelRegression Channel: the end point of a rolling least-squares fit of close over period bars, with bands multiplier root-mean…
• Raff Regression ChannelRaff Regression Channel: the same rolling least-squares centre line as the regression channel, but the channel half-width is th…
• STARC BandsSTARC Bands: a simple moving average of close with bands multiplier Average True Ranges above and below it.
• Fractal Chaos BandsFractal Chaos Bands: carries forward the most recent confirmed five-bar fractal high and fractal low, each held flat until a ne…
• Dynamic Zone BandsDynamic Zone Bands: a quantile envelope of close -- the upper band is the 1 - q quantile of the last period closes and the …
• TTM SqueezeTTM Squeeze: flags the bars on which the Bollinger band pair sits entirely inside the Keltner channel pair, the conventional si…
• Squeeze MomentumSqueeze Momentum: the TTM squeeze flag and its two band pairs, plus a momentum line -- the regression slope of the close's dist…
• Adaptive Price ZoneAdaptive Price Zone: a double-smoothed EMA of close as the centre line, with bands multiplier double-smoothed EMAs of the hig…