TrueRange

True Range — the single-bar volatility measure that ATR is the average of, exposed raw.

Quick reference

Field	Value
Family	Volatility & Bands
Input type	Candle (uses high, low, close)
Output type	f64
Output range	[0, ∞) (price scale)
Default parameters	none (no parameters)
Warmup period	1
Interpretation	Per-bar volatility including overnight gaps.

Formula

TR = max( high − low, |high − close_prev|, |low − close_prev| )

True Range is the greatest of the bar's own range and the two gaps to the previous close, so it captures volatility that opens between bars — an overnight gap — not only the range printed within a bar. The first bar has no previous close and falls back to high − low. Where Atr is the Wilder-smoothed average of this series, TrueRange exposes it raw, one value per bar.

Parameters

TrueRange takes no parameters — TrueRange::new() in Rust, wickra.TrueRange() in Python, new ta.TrueRange() in Node.

Inputs / Outputs

From crates/wickra-core/src/indicators/true_range.rs:

use wickra::{Indicator, TrueRange, Candle};
// TrueRange: Input = Candle, Output = f64
const _: fn(&mut TrueRange, Candle) -> Option<f64> = <TrueRange as Indicator>::update;

TrueRange is a candle-input indicator that reads high, low and close (the close drives the gap terms). Python's streaming update accepts a 6-tuple or a dict; the batch helper takes high, low, close numpy arrays. Node and WASM expose update(high, low, close) and the matching batch.

Warmup

TrueRange::new().warmup_period() == 1. It emits a value from the very first candle — that bar simply has no previous close and uses high − low.

Edge cases

• First bar. No previous close: TR = high − low.
• Gap. A bar that opens far from the prior close has a TR larger than its own high − low.
• Non-negative. TR is always >= 0.
• Reset. tr.reset() drops the previous close; the next bar restarts.

Examples

Rust

use wickra::{BatchExt, Candle, Indicator, TrueRange};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut tr = TrueRange::new();
    let out = tr.batch(&[
        Candle::new(11.0, 12.0, 8.0, 11.0, 1.0, 0)?,  // no prev close -> 12 - 8
        Candle::new(9.5, 10.0, 9.0, 9.5, 1.0, 1)?,    // prev close 11 -> max(1, 1, 2)
    ]);
    println!("{:?}", out);
    Ok(())
}

Output:

[Some(4.0), Some(2.0)]

Python

import numpy as np
import wickra as ta

tr = ta.TrueRange()
print(tr.batch(
    np.array([12.0, 10.0]), np.array([8.0, 9.0]), np.array([11.0, 9.5])
))

Output:

[4. 2.]

Node

const ta = require('wickra');
const tr = new ta.TrueRange();
console.log(tr.batch([12, 10], [8, 9], [11, 9.5]));

Output:

[ 4, 2 ]

Interpretation

Read TrueRange as raw per-bar volatility. It spikes on wide-range or gapping bars and shrinks in quiet stretches. Smoothing it with a moving average gives Atr; using it directly is useful for volatility-scaled position sizing or for spotting single outlier bars an average would hide.

Common pitfalls

• Confusing it with high − low. On a gap bar the True Range is larger — that is the whole point.
• Feeding it scalar prices. It needs the full high/low/close bar.

References

J. Welles Wilder Jr.'s True Range, from New Concepts in Technical Trading Systems (1978).

See also

• Indicator-Atr — the Wilder-smoothed average of the True Range.
• Indicator-ChaikinVolatility — a rate-of-change volatility measure.
• Indicators-Overview — the full taxonomy.