# Swing Structure Detector

`D08-F07-A15` · Geometric Chart Patterns → Market Structure, Breakouts, and Regimes · archetype `record-transform` · difficulty 2/5 · verification **verified**

Full page: https://docs.thefintechbuilder.com/geometric-chart-patterns/market-structure-breakouts-and-regimes/swing-structure-detector/
Agent skill: `npx skills add IslamBaraka90/Fintech-Algorithms-Library` — https://docs.thefintechbuilder.com/guides/agent-skill/

## Install and import

```bash
npm install fintech-algorithms
```

```ts
import { swingStructureDetector } from "fintech-algorithms/geometric-chart-patterns/market-structure-breakouts-and-regimes/swing-structure-detector";
```

## Signature

```ts
swingStructureDetector(input)
```

Confirms five-bar swing highs and lows and labels each one against the previous swing of the same kind - `HH`, `LH`, `HL`, `LL`, or `swing-high`/`swing-low` for the first of each. The confirmation is causal: a swing at bar p is only reported at bar p+2.

## Parameters

| Name | Type | Required | Notes |
| --- | --- | --- | --- |
| `input` | `TopicInput` | yes | `bars` is the required OHLCV history, strictly ordered by `timestamp` and on a single adjustment basis. The five-bar swing window is fixed and no `parameters` key changes it; `period` (default `20`, integer of at least 2) is validated by the family but unused here. |

## Returns

`TopicResult`

`series` and `latest` carry `swing_high`, `swing_low` and the string series `structure`. The warm-up is four bars: from index 4 `structure` reads `none` on bars with no confirmation, so `ready_at` is 4, while `swing_high` and `swing_low` stay null except on the bars that confirm one.

## Warm-up

The first `4 bars` positions are `null`. A centred five-bar window is impossible before index 4. From there `structure` is never null, so `ready_at` is 4 regardless of the data. When a high and a low confirm on the same bar the low's label is the one that survives.

## Errors

- When `bars` is empty or is not an array — throws Error
- When a bar's `high` or `low` is not a finite number — throws Error

## Complexity

Time `O(n)`, space `O(n)`.

## Worked example

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

`input`:

```json
{
  "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

```ts
swingStructureDetector(input)
```

### Returns

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

```json
{
  "topic_id": "D08-F07-A15",
  "title": "Swing Structure Detector",
  "state": "calculated",
  "ready": true,
  "ready_at": 4,
  "series": {
    "swing_high": [null, null, null, null, null, 105.01857496],
    "swing_low": [null, null, null, null, null, null],
    "structure": [null, null, null, null, "none", "swing-high"]
  },
  "latest": {
    "swing_high": null,
    "swing_low": null,
    "structure": "none"
  },
  "parameters": {},
  "diagnostics": {
    "causal": true,
    "input_count": 96
  }
}
```

## Verification and provenance

Tier: **verified** (via E).

The worked example below is the figure published in this algorithm's article, replayed and asserted by the test suite on every build. The arithmetic cannot drift without the build failing.

Both tiers guarantee the signature. Full explanation: https://docs.thefintechbuilder.com/guides/verification/

Generated from the docs.json payload shipped inside fintech-algorithms@0.13.0.
The signature and parameter list are checked against the compiled implementation at build time,
so a description that contradicts the code fails the build rather than reaching this file.

## Links

- Article (how it works, step by step): https://thefintechbuilder.com/geometric-chart-patterns/market-structure-breakouts-and-regimes/swing-structure-detector/
- Implementation source: https://github.com/IslamBaraka90/Fintech-Algorithms-Library/blob/main/src/geometric-chart-patterns/market-structure-breakouts-and-regimes/swing-structure-detector/impl.ts
- Package on npm: https://www.npmjs.com/package/fintech-algorithms
- Domain index for agents: https://docs.thefintechbuilder.com/geometric-chart-patterns/llms.txt