DragonflyDoji

Single-bar bullish reversal. Open, close and high sit at the top of the bar while a long lower shadow shows price was driven down hard and then bid all the way back to the open — buyers rejecting the lows.

Quick reference

Field	Value
Family	Candlestick Patterns
Input type	Candle
Output type	f64 — +1.0 bullish, 0.0 otherwise (never -1.0)
Output range	{0.0, +1.0}
Default parameters	none — DragonflyDoji::new()
Warmup period	1
Interpretation	Bullish rejection of the lows

Formula

range = high − low
doji          = |close − open| <= 0.1 · range
no upper wick = high − max(open, close) <= 0.1 · range
long lower    = min(open, close) − low  >= 0.5 · range

Bullish-only (never −1.0). The mirror is GravestoneDoji; the stricter variant is Takuri. See crates/wickra-core/src/indicators/dragonfly_doji.rs.

Parameters

None. Constructed with DragonflyDoji::new().

Signed ±1 encoding

Single-direction shape: +1.0 bullish, 0.0 no pattern — one feature-matrix dimension.

Inputs / Outputs

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

• Always emits a value. Never None; non-matching 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 no-match).

Warmup

warmup_period() == 1 — emits from the first candle (accessors_and_metadata).

Edge cases

• Upper shadow. A meaningful upper wick yields 0.0 (upper_shadow_yields_zero).
• Short lower shadow. Without the long lower wick the result is 0.0 (short_lower_shadow_yields_zero).
• Not a doji. A real body yields 0.0 (non_doji_yields_zero); a flat bar yields 0.0 (zero_range_yields_zero).
• Reset. reset() clears the has-emitted flag (reset_clears_state).

Examples

Rust

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

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut t = DragonflyDoji::new();
    // Body at the top (open=close=10, high=10.05), long lower shadow to 6.0.
    println!("{:?}", t.update(Candle::new(10.0, 10.05, 6.0, 10.0, 1.0, 0)?));
    Ok(())
}

Output:

Some(1.0)

range = 4.05, body 0, upper shadow 0.05, lower shadow 4.0 (> 0.5·range) — a dragonfly. This matches dragonfly_is_plus_one.

Python

import numpy as np
import wickra as ta

print(ta.DragonflyDoji().batch(
    np.array([10.0]), np.array([10.05]), np.array([6.0]), np.array([10.0])))  # [1.]

Node

const ta = require('wickra');
const t = new ta.DragonflyDoji();
console.log(t.update(10, 10.05, 6.0, 10)); // 1

Streaming

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

let mut t = DragonflyDoji::new();
let candle_stream: Vec<wickra::Candle> = Vec::new(); // your live OHLCV candle feed
for bar in candle_stream {
    if t.update(bar) == Some(1.0) { /* rejection of the lows */ }
}

Interpretation

1. Bottom reversal. A long lower shadow recovered to the high is a bullish rejection — strongest at support or the foot of a decline.
2. Confirm. A single doji is weak evidence; pair with a follow-through up candle or support context.

Common pitfalls

• No location context. A dragonfly mid-range means little.
• Confusing with a hammer. A Hammer has a small body; a dragonfly's body is effectively zero (a doji).

References

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

See also

• GravestoneDoji — the bearish mirror.
• Takuri — stricter dragonfly with a very long lower shadow.
• Hammer — small-bodied bullish cousin.
• Indicators-Overview — the full taxonomy.