# Trend/Range Regime Classifier

`D08-F07-A12` · 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/trend-range-regime-classifier/
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 { trendRangeRegimeClassifier } from "fintech-algorithms/geometric-chart-patterns/market-structure-breakouts-and-regimes/trend-range-regime-classifier";
```

## Signature

```ts
trendRangeRegimeClassifier(input)
```

Labels each bar `trend`, `range` or `uncertain` by requiring two independent readings to agree: efficiency ratio at or above 0.55 with Choppiness at or below 45 gives `trend`, efficiency at or below 0.25 with Choppiness at or above 55 gives `range`, and anything else is `uncertain`.

## Parameters

| Name | Type | Required | Notes |
| --- | --- | --- | --- |
| `input` | `TopicInput` | yes | `bars` is the required OHLCV history, strictly ordered by `timestamp` and on a single adjustment basis. `parameters.period` (default `20`, integer of at least 2) sets both inputs - it is forwarded verbatim to the Choppiness Index implementation, which reads no other key. The four thresholds are fixed in the implementation. |

## Returns

`TopicResult`

`series` and `latest` carry `efficiency`, `choppiness` and the string series `regime`. The warm-up is uneven: `choppiness` starts at `period - 1` and `efficiency` at `period`, so `ready_at` is 19 with the default while the `regime` label itself stays null until index 20.

## Warm-up

The first `period - 1 bars for choppiness, period bars for efficiency and regime` positions are `null`. `ready_at` reports the earliest non-null across all series, which is `choppiness` at index `period - 1`. A caller reading `regime` should wait one bar longer, since the label is null whenever either input is.

## Errors

- When `period` is supplied as a non-integer or as a value below 2 — throws Error
- When a bar's `high`, `low`, or `close` is not a finite number — throws Error

## Complexity

Time `O(n × period)`, 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
trendRangeRegimeClassifier(input)
```

### Returns

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

```json
{
  "topic_id": "D08-F07-A12",
  "title": "Trend/Range Regime Classifier",
  "state": "calculated",
  "ready": true,
  "ready_at": 19,
  "series": {
    "efficiency": [null, null, null, null, null, null],
    "choppiness": [null, null, null, null, null, null],
    "regime": [null, null, null, null, null, null]
  },
  "latest": {
    "efficiency": 0.08092573520497529,
    "choppiness": 58.89834097590164,
    "regime": "range"
  },
  "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/trend-range-regime-classifier/
- Implementation source: https://github.com/IslamBaraka90/Fintech-Algorithms-Library/blob/main/src/geometric-chart-patterns/market-structure-breakouts-and-regimes/trend-range-regime-classifier/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