Tristar

Three consecutive Doji where the middle gaps away from its neighbours — a rare top (middle above) or bottom (middle below) reversal.

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)
mid = body centre of the middle doji,  n1/n3 = body centres of the outer two
Bearish (−1): mid > n1 AND mid > n3   (middle star on top)
Bullish (+1): mid < n1 AND mid < n3   (middle star on bottom)
otherwise 0

A Tristar is three indecision candles in a row with the middle one isolated above (top) or below (bottom) the others — a strong signal of exhaustion after a trend. Source: crates/wickra-core/src/indicators/tristar.rs.

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) → 1-D ndarray; 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 highest → −1 (bearish_tristar_top pins this).
• Bullish bottom. Middle doji lowest → +1 (bullish_tristar_bottom pins this).
• 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 highest
    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))  # [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. This uses body-centre ordering rather than strict gaps to be robust on gapless (24/7) markets.

References

Nison, S. (1991), Japanese Candlestick Charting Techniques.

See also

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