DojiStar

Two-bar reversal warning. A long trending body is followed by a doji whose tiny body gaps away in the direction of the trend — the indecision hinting the move is about to turn.

Quick reference

Field	Value
Family	Candlestick Patterns
Input type	Candle
Output type	f64 — +1.0 bullish, -1.0 bearish, 0.0 otherwise
Output range	{-1.0, 0.0, +1.0}
Default parameters	none — DojiStar::new()
Warmup period	2 (first bar always 0.0)
Interpretation	Reversal warning; the confirming bar is the morning/evening star

Formula

long body = |close − open| >= 0.5 · (high − low)   (bar1)
doji      = |close − open| <= 0.1 · (high − low)   (bar2)
bullish (+1.0): bar1 black, doji body gaps DOWN below it  (max(o2,c2) < close1)
bearish (-1.0): bar1 white, doji body gaps UP above it    (min(o2,c2) > close1)

A doji star is the first two bars of a morning/evening star — a warning, not a confirmed reversal, since the third (confirming) bar has not yet arrived. See crates/wickra-core/src/indicators/doji_star.rs.

Parameters

None. Constructed with DojiStar::new().

Signed ±1 encoding

Emits the uniform candlestick sign convention — +1.0 bullish, −1.0 bearish, 0.0 no pattern — a single feature-matrix dimension.

Inputs / Outputs

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

• Always emits a value. Never None; warmup and no-match bars return 0.0.
• Node. update(open, high, low, close) → number; batch(open, high, low, close) → Array<number>.
• Python. update(candle) → float; batch(open, high, low, close) → 1-D numpy.ndarray (0.0 on warmup / no-match).

Warmup

warmup_period() == 2. The first bar returns 0.0 (first_bar_returns_zero, accessors_and_metadata).

Edge cases

• Second bar must be a doji. A real-bodied second bar yields 0.0 (second_bar_not_doji_yields_zero).
• Gap required. Without the body gap in the trend direction the result is 0.0 (no_gap_yields_zero).
• First body must be long. A short first body yields 0.0 (short_first_body_yields_zero).
• Reset. reset() clears the one-bar cache (reset_clears_state).

Examples

Rust

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

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut t = DojiStar::new();
    println!("{:?}", t.update(Candle::new(20.0, 20.2, 14.8, 15.0, 1.0, 0)?)); // long black
    println!("{:?}", t.update(Candle::new(13.0, 13.1, 12.9, 13.0, 1.0, 1)?)); // doji, gaps down
    Ok(())
}

Output:

Some(0.0)
Some(1.0)

The doji's body (≈13) gaps below the black bar's close (15) — a bullish doji star. This matches bullish_doji_star_is_plus_one.

Python

import numpy as np
import wickra as ta

o = np.array([20.0, 13.0])
h = np.array([20.2, 13.1])
l = np.array([14.8, 12.9])
c = np.array([15.0, 13.0])

print(ta.DojiStar().batch(o, h, l, c))  # [0. 1.]

Node

const ta = require('wickra');
const t = new ta.DojiStar();
t.update(20, 20.2, 14.8, 15);
console.log(t.update(13, 13.1, 12.9, 13)); // 1

Streaming

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

let mut t = DojiStar::new();
let candle_stream: Vec<wickra::Candle> = Vec::new(); // your live OHLCV candle feed
for bar in candle_stream {
    match t.update(bar) {
        Some(1.0)  => { /* bullish doji star — watch for confirmation */ }
        Some(-1.0) => { /* bearish doji star */ }
        _ => {}
    }
}

Interpretation

1. Early warning. The gapped doji after a strong body signals momentum stalling — but it is only the first two bars of a star.
2. Wait for confirmation. MorningDojiStar / EveningDojiStar add the third bar that confirms the turn; trade those, treat the doji star as a heads-up.

Common pitfalls

• Treating it as a confirmed reversal. It is a two-bar precursor, not the full star.
• No trend context. Only meaningful after a directional move.

References

• Steve Nison, Japanese Candlestick Charting Techniques (1991).

See also

• MorningDojiStar / EveningDojiStar — confirmed three-bar stars.
• AbandonedBaby — the full-gap island version.
• Indicators-Overview — the full taxonomy.