Takuri

Single-bar bullish reversal — a stricter Dragonfly Doji. Open, close and high sit at the very top with a negligible upper shadow, while an exceptionally long lower shadow shows price was driven down sharply and then bid all the way back: an emphatic rejection of 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 — Takuri::new()
Warmup period	1
Interpretation	Bullish rejection of the lows; stronger than a plain dragonfly

Formula

range = high − low
doji body:        |close − open| <= 0.1  · range
negligible upper: high − max(open, close) <= 0.05 · range
very long lower:  min(open, close) − low  >= 0.7  · range

Bullish-only (never −1.0). The tighter upper-shadow ceiling (5 % vs the dragonfly's 10 %) and longer lower-shadow floor (70 % vs 50 %) make Takuri a strict subset of DragonflyDoji. Thresholds are geometric, not TA-Lib rolling averages. See crates/wickra-core/src/indicators/takuri.rs.

Parameters

None. Constructed with Takuri::new().

Signed ±1 encoding

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

Inputs / Outputs

use wickra::{Indicator, Takuri, Candle};
// Takuri: Input = Candle, Output = f64
const _: fn(&mut Takuri, Candle) -> Option<f64> = <Takuri 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 — a single-bar pattern emits from the first candle (accessors_and_metadata).

Edge cases

• Body too large. A bar that is not a doji yields 0.0 (non_doji_body_yields_zero).
• Upper shadow. Any meaningful upper shadow disqualifies it (upper_shadow_yields_zero); even a bar that would pass as a dragonfly (upper shadow ≈ 7 % of range) fails Takuri's tighter 5 % ceiling (dragonfly_but_not_takuri_yields_zero).
• Zero range. 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, Indicator, Takuri};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut t = Takuri::new();
    // Body at the top (open=close=10, high=10.05), very long lower shadow to 7.0.
    println!("{:?}", t.update(Candle::new(10.0, 10.05, 7.0, 10.0, 1.0, 0)?));
    Ok(())
}

Output:

Some(1.0)

range = 3.05, body 0, upper shadow 0.05 (< 0.05·3.05), lower shadow 3.0 (> 0.7·3.05). This matches the takuri_is_plus_one unit test.

Python

import numpy as np
import wickra as ta

o = np.array([10.0])
h = np.array([10.05])
l = np.array([7.0])
c = np.array([10.0])

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

Node

const ta = require('wickra');
const t = new ta.Takuri();
console.log(t.update(10, 10.05, 7.0, 10)); // 1

Streaming

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

let mut t = Takuri::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) { /* strong rejection of the lows */ }
}

Interpretation

1. Rejection of the lows. The deep lower shadow that closes back at the high is a hard bid response — a bullish reversal cue, strongest at the bottom of a downtrend or at support.
2. Stronger than a dragonfly. Because Takuri demands a longer lower shadow and a cleaner top, a Takuri print is a higher-conviction version of the DragonflyDoji signal.
3. Confirm. Pair with support context or a follow-through up candle.

Common pitfalls

• Treating any dragonfly as a Takuri. Most dragonflies do not clear Takuri's tighter thresholds; the distinction is intentional.
• No location context. A Takuri mid-range is far less meaningful than one at a tested low.

References

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

See also

• DragonflyDoji — the looser parent pattern.
• Hammer — small body at the top with a long lower shadow.
• Indicators-Overview — the full taxonomy.