ThreeLineStrike

Four-bar pattern: three candles marching in one direction (a three-soldiers / three-crows run) followed by a fourth, opposite-colour candle that opens beyond the third and closes back past the first candle's open — "striking" through the whole run in a single bar.

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 — ThreeLineStrike::new()
Warmup period	4 (first three bars always 0.0)
Interpretation	Classically a continuation; the strike is a one-bar pullback

Formula

Bullish (+1.0):
  bar1..bar3 green, each opening inside the prior body and closing higher
  bar4 red & opens above bar3's close & closes below bar1's open

Bearish (-1.0): the mirror — three falling red candles struck by a green
  bar4 that opens below bar3's close and closes above bar1's open

The sign follows the three-candle run, not the strike candle: a bullish three-line strike (+1.0) is read as bullish continuation despite the red fourth bar. Thresholds are geometric, not TA-Lib rolling averages. See crates/wickra-core/src/indicators/three_line_strike.rs.

Parameters

None. Constructed with ThreeLineStrike::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, ThreeLineStrike, Candle};
// ThreeLineStrike: Input = Candle, Output = f64
const _: fn(&mut ThreeLineStrike, Candle) -> Option<f64> = <ThreeLineStrike 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() == 4. The first three bars return 0.0 (first_three_bars_return_zero, accessors_and_metadata).

Edge cases

• Strike must clear the first open. A fourth candle that fails to close past the first candle's open yields 0.0 (strike_not_clearing_first_open_yields_zero).
• Both directions. Bullish and bearish variants are pinned by bullish_three_line_strike_is_plus_one and bearish_three_line_strike_is_minus_one.
• Reset. reset() clears the three-bar cache (reset_clears_state).

Examples

Rust

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

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut t = ThreeLineStrike::new();
    println!("{:?}", t.update(Candle::new(10.0, 11.1, 9.9, 11.0, 1.0, 0)?));  // green
    println!("{:?}", t.update(Candle::new(10.5, 12.1, 10.4, 12.0, 1.0, 1)?)); // green, higher
    println!("{:?}", t.update(Candle::new(11.5, 13.1, 11.4, 13.0, 1.0, 2)?)); // green, higher
    println!("{:?}", t.update(Candle::new(13.5, 13.6, 9.4, 9.5, 1.0, 3)?));   // red, strikes through
    Ok(())
}

Output:

Some(0.0)
Some(0.0)
Some(0.0)
Some(1.0)

The fourth candle opens at 13.5 (above bar3's close 13.0) and closes at 9.5 (below bar1's open 10.0), striking through the three-soldier run. This matches bullish_three_line_strike_is_plus_one.

Python

import numpy as np
import wickra as ta

o = np.array([10.0, 10.5, 11.5, 13.5])
h = np.array([11.1, 12.1, 13.1, 13.6])
l = np.array([9.9,  10.4, 11.4, 9.4])
c = np.array([11.0, 12.0, 13.0, 9.5])

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

Node

const ta = require('wickra');
const t = new ta.ThreeLineStrike();
t.update(10, 11.1, 9.9, 11);
t.update(10.5, 12.1, 10.4, 12);
t.update(11.5, 13.1, 11.4, 13);
console.log(t.update(13.5, 13.6, 9.4, 9.5)); // 1

Streaming

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

let mut t = ThreeLineStrike::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 continuation — buy-the-dip context */ }
        Some(-1.0) => { /* bearish continuation */ }
        _ => {}
    }
}

Interpretation

1. Continuation, not reversal (classically). Despite the dramatic strike candle, the historical read is that the trend resumes — the strike is a one-bar shake-out. Many modern studies dispute its edge, so treat it as context, not a signal on its own.
2. Sign = the run. A +1.0 means the three-soldier run was bullish; the red strike bar is the pullback inside it.
3. Confirm. Wait for the trend to actually resume before acting.

Common pitfalls

• Reading the strike candle's colour as the signal. The output sign follows the three-bar run, not the fourth bar.
• Over-trusting it. Empirical reliability is mixed; use only with corroborating context.

References

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

See also

• ThreeSoldiersOrCrows — the three-bar run the strike acts on.
• RisingThreeMethods — a cleaner continuation pattern.
• Indicators-Overview — the full taxonomy.