AdvanceBlock

Three-bar bearish warning. Three green candles still push to higher closes, but visibly run out of steam — each real body shrinks while the upper shadows lengthen, hinting the advance is about to stall.

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 — AdvanceBlock::new()
Warmup period	3 (first two bars always 0.0)
Interpretation	Bearish exhaustion warning near the top of an advance

Formula

all three green & higher closes
each opens inside the prior body
shrinking bodies:  body3 < body2 < body1
upper shadow of bar3 >= upper shadow of bar2, and bar3 has an upper shadow

Bearish-only (never +1.0). The combination of shrinking bodies and growing upper wicks while still closing higher is the tell that demand is fading. See crates/wickra-core/src/indicators/advance_block.rs.

Parameters

None. Constructed with AdvanceBlock::new().

Signed ±1 encoding

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

Inputs / Outputs

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

• A healthy advance does not fire. Three strong, non-shrinking green candles yield 0.0 (strong_advance_yields_zero).
• Upper shadows must grow. Without the lengthening upper wick on the third candle the result is 0.0 (no_upper_shadow_growth_yields_zero).
• Reset. reset() clears the two-bar cache (reset_clears_state).

Examples

Rust

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

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut t = AdvanceBlock::new();
    println!("{:?}", t.update(Candle::new(10.0, 13.1, 9.9, 13.0, 1.0, 0)?));  // strong green
    println!("{:?}", t.update(Candle::new(12.0, 14.3, 11.9, 14.0, 1.0, 1)?)); // smaller body
    println!("{:?}", t.update(Candle::new(13.5, 15.0, 13.4, 14.5, 1.0, 2)?)); // tiny body, long upper wick
    Ok(())
}

Output:

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

Bodies shrink 3.0 → 2.0 → 1.0 while the third candle sprouts a 0.5 upper shadow — an advance block. This matches advance_block_is_minus_one.

Python

import numpy as np
import wickra as ta

o = np.array([10.0, 12.0, 13.5])
h = np.array([13.1, 14.3, 15.0])
l = np.array([9.9,  11.9, 13.4])
c = np.array([13.0, 14.0, 14.5])

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

Node

const ta = require('wickra');
const t = new ta.AdvanceBlock();
t.update(10, 13.1, 9.9, 13);
t.update(12, 14.3, 11.9, 14);
console.log(t.update(13.5, 15, 13.4, 14.5)); // -1

Streaming

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

let mut t = AdvanceBlock::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) { /* advance is stalling — protect longs */ }
}

Interpretation

1. Fading demand. Higher closes on shrinking bodies and rising upper wicks reveal supply meeting the advance — a caution flag near a top.
2. Warning, not trigger. Like Stalled Pattern it argues for caution, not an immediate short.
3. Best near resistance. Most meaningful at the top of an extended run.

Common pitfalls

• Confusing it with healthy three soldiers. A strong, even three-soldier advance is bullish; Advance Block is specifically the weakening version.
• Expecting an instant reversal. It flags exhaustion, not a confirmed turn.

References

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

See also

• StalledPattern — sibling deliberation top.
• ThreeSoldiersOrCrows — the healthy advance this warns is tiring.
• Indicators-Overview — the full taxonomy.