ThreeStarsInSouth

Rare three-bar bullish reversal. Three shrinking black candles, each carving a higher low and contracting toward a tiny black marubozu, show selling pressure draining away at the bottom of a decline.

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	tolerance = 0.001 (10 bps); bindings use the default
Warmup period	3 (first two bars always 0.0)
Interpretation	Bullish exhaustion bottom after a decline

Formula

tol = tolerance · max(|bar3.high|, |bar3.low|)
all three red:  close < open
bar1 long lower shadow:  (bar1.close − bar1.low) >= (bar1.open − bar1.close)
bar2 opens inside bar1's body, higher low, smaller body, closes above bar1.close
bar3 small black marubozu (upper & lower shadow <= tol) inside bar2's range

Bullish-only (never −1.0). Three black candles whose ranges contract and lows rise show sellers losing ground — the southern stars fading. See crates/wickra-core/src/indicators/three_stars_in_south.rs.

Parameters

Name	Type	Default	Valid range	Source
tolerance	f64	0.001	[0.0, 1.0)	ThreeStarsInSouth::with_tolerance (three_stars_in_south.rs)

with_tolerance outside [0, 1) errors; pinned by rejects_invalid_tolerance and accepts_valid_tolerance. Python (ta.ThreeStarsInSouth()) and Node (new ta.ThreeStarsInSouth()) construct with the default tolerance.

Signed ±1 encoding

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

Inputs / Outputs

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

• Third candle must be a clean small marubozu. Any meaningful shadow on the third candle yields 0.0 (third_with_shadow_yields_zero).
• Lows must rise. A lower low on a later candle breaks the contraction (lower_low_yields_zero).
• Reset. reset() clears the two-bar cache (reset_clears_state).

Examples

Rust

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

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut t = ThreeStarsInSouth::new();
    println!("{:?}", t.update(Candle::new(20.0, 20.1, 8.0, 15.0, 1.0, 0)?));  // long lower shadow
    println!("{:?}", t.update(Candle::new(18.0, 18.1, 12.0, 16.0, 1.0, 1)?)); // smaller, higher low
    println!("{:?}", t.update(Candle::new(15.0, 15.0, 14.0, 14.0, 1.0, 2)?)); // tiny black marubozu
    Ok(())
}

Output:

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

Lows rise 8 → 12 → 14 while the bodies shrink to a tiny black marubozu — three stars in the south. This matches three_stars_in_south_is_plus_one.

Python

import numpy as np
import wickra as ta

o = np.array([20.0, 18.0, 15.0])
h = np.array([20.1, 18.1, 15.0])
l = np.array([8.0,  12.0, 14.0])
c = np.array([15.0, 16.0, 14.0])

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

Node

const ta = require('wickra');
const t = new ta.ThreeStarsInSouth();
t.update(20, 20.1, 8, 15);
t.update(18, 18.1, 12, 16);
console.log(t.update(15, 15, 14, 14)); // 1

Streaming

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

let mut t = ThreeStarsInSouth::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) { /* selling exhaustion at the lows */ }
}

Interpretation

1. Exhaustion bottom. Three black candles that keep shrinking and lifting their lows show sellers unable to extend — a bullish reversal cue after a decline.
2. Very rare. Like Concealing Baby Swallow, prints are scarce; treat as a prompt to look for confirmation.
3. Confirm. A white follow-through candle or a momentum turn strengthens the read.

Common pitfalls

• Demanding a perfect third marubozu. It only needs to be a small black body with shadows within tolerance.
• No downtrend context. Only meaningful at the foot of a decline.

References

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

See also

• ConcealingBabySwallow — another rare multi-black bottoming pattern.
• LadderBottom — a five-bar bottoming reversal.
• Indicators-Overview — the full taxonomy.