MatchingLow

Two-bar bullish reversal. Two black candles in a decline close at the same level: the second sell-off cannot push price any lower, so the matching closes mark a support floor.

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 — MatchingLow::new()
Warmup period	2 (first bar always 0.0)
Interpretation	Bullish support floor after a decline

Formula

bar1, bar2 both black
equal closes = |close2 − close1| <= 0.05 · mean(range1, range2)

Bullish-only (never −1.0). Two black closes at the same level mark a floor sellers could not break. The two-bar precursor to the three-bar StickSandwich. See crates/wickra-core/src/indicators/matching_low.rs.

Parameters

None. Constructed with MatchingLow::new().

Signed ±1 encoding

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

Inputs / Outputs

use wickra::{Indicator, MatchingLow, Candle};
// MatchingLow: Input = Candle, Output = f64
const _: fn(&mut MatchingLow, Candle) -> Option<f64> = <MatchingLow 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() == 2. The first bar returns 0.0 (first_bar_returns_zero, accessors_and_metadata).

Edge cases

• Closes must match. A different second close yields 0.0 (different_close_yields_zero).
• Both bars must be black. A white second bar yields 0.0 (second_bar_white_yields_zero).
• Reset. reset() clears the one-bar cache (reset_clears_state).

Examples

Rust

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

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut t = MatchingLow::new();
    println!("{:?}", t.update(Candle::new(15.0, 15.1, 9.9, 10.0, 1.0, 0)?)); // black, close 10
    println!("{:?}", t.update(Candle::new(13.0, 13.1, 9.9, 10.0, 1.0, 1)?)); // black, close 10
    Ok(())
}

Output:

Some(0.0)
Some(1.0)

Both black candles close at 10.0 — a matching low. This matches matching_low_is_plus_one.

Python

import numpy as np
import wickra as ta

o = np.array([15.0, 13.0])
h = np.array([15.1, 13.1])
l = np.array([9.9,  9.9])
c = np.array([10.0, 10.0])

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

Node

const ta = require('wickra');
const t = new ta.MatchingLow();
t.update(15, 15.1, 9.9, 10);
console.log(t.update(13, 13.1, 9.9, 10)); // 1

Streaming

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

let mut t = MatchingLow::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) { /* support floor formed — watch for a turn */ }
}

Interpretation

1. Floor held. Two black sessions closing at the same level show sellers unable to extend — a soft bullish reversal cue after a decline.
2. Soft signal. The matched close is the whole pattern; confirm with a follow-through up candle.
3. Best at support. Most meaningful after a decline.

Common pitfalls

• Demanding tick-equal closes. They only need to match within 5 % of the mean range.
• No downtrend context. Only meaningful inside a decline.

References

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

See also

• StickSandwich — the three-bar version.
• HomingPigeon — another soft two-bar bottoming pattern.
• Indicators-Overview — the full taxonomy.