Tristar

Three consecutive Doji where the middle one's body gaps away from the first — a rare top (middle gaps above) or bottom (middle gaps below) reversal (Nison; TA-Lib CDLTRISTAR).

Quick reference

Field	Value
Family	Candlestick Patterns
Input type	Candle (open / high / low / close)
Output type	f64 (signed signal)
Output range	{−1, 0, +1}
Default parameters	None (doji threshold fixed at 0.1)
Warmup period	3
Interpretation	+1 bullish bottom; −1 bearish top.

Formula

all three bars are doji:  |close − open| <= 0.1 * (high − low),  high > low
Bearish (−1): min(o2, c2) > max(o1, c1)     (middle body gaps above the first)
          AND max(o3, c3) < max(o2, c2)     (third body top below the middle's)
Bullish (+1): max(o2, c2) < min(o1, c1)     (middle body gaps below the first)
          AND min(o3, c3) > min(o2, c2)     (third body bottom above the middle's)
otherwise 0

A Tristar is three indecision candles in a row with the middle one's real body gapping above (top) or below (bottom) the first — the body gap of the middle doji is the defining feature — while the third doji fails to extend past the middle one. It is a strong signal of exhaustion after a trend. Source: crates/wickra-core/src/indicators/tristar.rs.

TA-Lib parity. On the TA-Lib reference pattern series the signals are identical to CDLTRISTAR (±1 here, ±100 there). TA-Lib sizes bodies and shadows against 5- or 10-bar rolling averages ("candle settings"), while Wickra sizes them against the pattern's own bars.

Parameters

Name	Type	Default	Valid range	Source	Description
—	—	—	—	None.	Tristar is parameter-free; the doji body/range threshold is fixed at 0.1.

Signed ±1 encoding

+1.0 bullish (bottom), −1.0 bearish (top), 0.0 no pattern (warmup emits None).

Inputs / Outputs

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

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

A Candle in, an Option<f64> out. Python update(candle) / batch(open, high, low, close) → array.array('d'); Node update(open, high, low, close) / batch(...).

Warmup

warmup_period() == 3. Two candles seed the buffer (first_two_bars_seed_without_signal pins this).

Edge cases

• Bearish top. Middle doji body gaps above the first, third body top below the middle's → −1 (bearish_tristar_top pins this).
• Bullish bottom. Middle doji body gaps below the first, third body bottom above the middle's → +1 (bullish_tristar_bottom pins this).
• No gap → 0. A middle doji whose body overlaps the first doji's body is not a star, however its centre compares.
• Third bar. Only the third doji's body top (bearish) / bottom (bullish) is checked against the middle; it need not gap away from the middle.
• Non-doji → 0. Any solid body breaks the pattern (non_doji_is_zero pins this).
• Finiteness. Candle::new rejects non-finite fields, so no in-method guard is needed.
• Reset. t.reset() clears the two prior candles and the last value (reset_clears_state).

Examples

Rust

use wickra::{Candle, Indicator, Tristar};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut t = Tristar::new();
    let doji = |mid: f64| Candle::new(mid, mid + 1.0, mid - 1.0, mid + 0.02, 0.0, 0).unwrap();
    t.update(doji(100.0));
    t.update(doji(105.0)); // middle body gaps above the first
    println!("{:?}", t.update(doji(100.0))); // Some(-1.0)
    Ok(())
}

Output:

Some(-1.0)

Python

import numpy as np
import wickra as ta

t = ta.Tristar()
o = np.array([100, 105, 100], float); h = o + 1; l = o - 1; c = o + 0.02
print(t.batch(o, h, l, c))  # array('d', [nan, nan, -1.0])

Node

const ta = require('wickra');
const t = new ta.Tristar();
t.update(100, 101, 99, 100.02); t.update(105, 106, 104, 105.02);
console.log(t.update(100, 101, 99, 100.02)); // -1

Streaming

use wickra::{Candle, Indicator, Tristar};

let mut t = Tristar::new();
let feed: Vec<Candle> = Vec::new(); // your live stream
for candle in feed {
    match t.update(candle) {
        Some(1.0)  => println!("tristar bottom"),
        Some(-1.0) => println!("tristar top"),
        _ => {}
    }
}

Streaming update and batch are equivalent tick-for-tick (batch_equals_streaming pins this).

Interpretation

1. Exhaustion. Three dojis after a trend signal that momentum has stalled; the star geometry hints at the reversal direction.
2. Confirmation. Wait for a confirming bar beyond the pattern before acting — Tristar is rare and prone to noise.
3. Context. Most meaningful at a tested support/resistance level.

Common pitfalls

• Rare and finicky. True three-doji clusters are uncommon; the threshold choice matters.
• Needs trend context. A Tristar mid-range is meaningless; it is a reversal pattern.
• Gap definition. The middle doji's body must gap clear of the first doji's body (shadows may overlap). On gapless (24/7) markets, where each open equals the prior close, true body gaps are rare and the pattern will seldom fire.

References

Nison, S. (1991), Japanese Candlestick Charting Techniques. TA-Lib CDLTRISTAR — the body-gap rule implemented here.

See also

• Indicator-Doji — the building-block indecision candle.
• Indicator-MorningEveningStar — body-star reversal.
• Indicator-HaramiCross — doji-inside reversal.
• Indicators-Overview — the full taxonomy.