DownsideGapThreeMethods

Three-bar bearish continuation. Two black candles decline with a downside body gap between them, then a white candle opens inside the second body and closes inside the first, partially filling the gap without erasing the decline.

Quick reference

Field	Value
Family	Candlestick Patterns
Input type	Candle
Output type	f64 — -1.0 bearish, 0.0 otherwise (never +1.0)
Output range	{-1.0, 0.0}
Default parameters	none — DownsideGapThreeMethods::new()
Warmup period	3 (first two bars always 0.0)
Interpretation	Downtrend continuation; the gap is defended, not closed

Formula

bar1 black, bar2 black
downside body gap:  open2 < close1           (bar2's body entirely below bar1's)
bar3 white, opens within bar2's body:  close2 < open3 < open2
bar3 closes within bar1's body:        close1 < close3 < open1

Bearish-only (never +1.0); the bullish mirror is UpsideGapThreeMethods. The white third candle bounces into the gap but only as far as the first body — the decline survives. Thresholds are geometric, not TA-Lib rolling averages. See crates/wickra-core/src/indicators/downside_gap_three_methods.rs.

Parameters

None. Constructed with DownsideGapThreeMethods::new().

Signed ±1 encoding

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

Inputs / Outputs

use wickra::{Indicator, DownsideGapThreeMethods, Candle};
// DownsideGapThreeMethods: Input = Candle, Output = f64
const _: fn(&mut DownsideGapThreeMethods, Candle) -> Option<f64> = <DownsideGapThreeMethods 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() == 3. The first two bars return 0.0 (first_two_bars_return_zero, accessors_and_metadata).

Edge cases

• Leading bars must be black. A white first/second candle yields 0.0 (non_black_first_bars_yield_zero).
• Gap required. No downside body gap between bars 1 and 2 → 0.0 (no_gap_yields_zero).
• Third candle must be white and land in the bodies. A black third candle (third_bar_not_white_yields_zero) or one closing outside the first body (third_bar_outside_bodies_yields_zero) yields 0.0.
• Reset. reset() clears the two-bar cache (reset_clears_state).

Examples

Rust

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

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut t = DownsideGapThreeMethods::new();
    println!("{:?}", t.update(Candle::new(13.0, 13.2, 11.8, 12.0, 1.0, 0)?)); // black
    println!("{:?}", t.update(Candle::new(11.0, 11.1, 9.8, 10.0, 1.0, 1)?));  // black, gaps down
    println!("{:?}", t.update(Candle::new(10.5, 12.6, 10.4, 12.5, 1.0, 2)?)); // white, fills partly
    Ok(())
}

Output:

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

The third candle opens at 10.5 inside bar2's body (10, 11) and closes at 12.5 inside bar1's body (12, 13) — a downside gap three methods. This matches downside_gap_three_methods_is_minus_one.

Python

import numpy as np
import wickra as ta

o = np.array([13.0, 11.0, 10.5])
h = np.array([13.2, 11.1, 12.6])
l = np.array([11.8, 9.8,  10.4])
c = np.array([12.0, 10.0, 12.5])

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

Node

const ta = require('wickra');
const t = new ta.DownsideGapThreeMethods();
t.update(13, 13.2, 11.8, 12);
t.update(11, 11.1, 9.8, 10);
console.log(t.update(10.5, 12.6, 10.4, 12.5)); // -1

Streaming

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

let mut t = DownsideGapThreeMethods::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) { /* downtrend continuation — gap defended */ }
}

Interpretation

1. Continuation, not reversal. The white bounce candle tests the gap but the decline holds; read it as a chance to stay short inside a downtrend.
2. Contrast with Tasuki. TasukiGap leaves the gap open; here the bounce partially fills it yet still stops at the first body.
3. Confirm the trend. Use within an established downtrend; pair with a trend filter.

Common pitfalls

• Mistaking it for a reversal. A white candle after two black ones looks bullish, but the contained bounce is a continuation tell.
• No trend context. Meaningless in a sideways range.

References

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

See also

• UpsideGapThreeMethods — the bullish mirror.
• TasukiGap — gap continuation that leaves the gap open.
• FallingThreeMethods — non-gap bearish continuation.
• Indicators-Overview — the full taxonomy.