TwoCrows

Three-bar bearish reversal after an advance. A long white candle is followed by two black candles: the first gaps its body up, the second opens inside that body and closes back down inside the white body — two crows settling on the highs.

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 — TwoCrows::new()
Warmup period	3 (first two bars always 0.0)
Interpretation	Bearish reversal at the top of an advance

Formula

bar1 green (long white)
bar2 red & its body gaps up above bar1's body:  bar2.close > bar1.close
bar3 red & opens inside bar2's body:             bar2.close < bar3.open  < bar2.open
         & closes inside bar1's body:            bar1.open  < bar3.close < bar1.close

Bearish-only (never +1.0). The second crow erasing the gap by closing back inside the white body is the reversal tell. Thresholds are geometric, not TA-Lib rolling averages. See crates/wickra-core/src/indicators/two_crows.rs.

Parameters

None. Constructed with TwoCrows::new().

Signed ±1 encoding

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

Inputs / Outputs

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

• No upside gap. If the first black candle does not gap its body above the white body, the result is 0.0 (no_gap_up_yields_zero).
• Third close not inside the first body. A third close that does not return into the white body yields 0.0 (third_close_below_first_body_yields_zero).
• Reset. reset() clears the two-bar cache (reset_clears_state).

Examples

Rust

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

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut t = TwoCrows::new();
    println!("{:?}", t.update(Candle::new(10.0, 12.2, 9.9, 12.0, 1.0, 0)?));  // long white
    println!("{:?}", t.update(Candle::new(14.0, 14.2, 12.9, 13.0, 1.0, 1)?)); // black, gaps up
    println!("{:?}", t.update(Candle::new(13.5, 13.6, 10.9, 11.0, 1.0, 2)?)); // black, back inside
    Ok(())
}

Output:

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

The second crow opens at 13.5 inside the first crow's body (13, 14) and closes at 11.0 inside the white body (10, 12) — Two Crows. This matches two_crows_is_minus_one.

Python

import numpy as np
import wickra as ta

o = np.array([10.0, 14.0, 13.5])
h = np.array([12.2, 14.2, 13.6])
l = np.array([9.9,  12.9, 10.9])
c = np.array([12.0, 13.0, 11.0])

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

Node

const ta = require('wickra');
const t = new ta.TwoCrows();
t.update(10, 12.2, 9.9, 12);
t.update(14, 14.2, 12.9, 13);
console.log(t.update(13.5, 13.6, 10.9, 11)); // -1

Streaming

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

let mut t = TwoCrows::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) { /* bearish reversal candidate at the highs */ }
}

Interpretation

1. Top reversal. Meaningful at the top of an advance: the failed gap-up and the close back into the white body show buyers losing the highs.
2. Softer than engulfing. A two-crows signal is a caution flag; confirm with a follow-through down candle or a momentum roll-over.
3. Stronger cousin. UpsideGapTwoCrows keeps the gap open and is the more strictly-defined sibling.

Common pitfalls

• No uptrend context. As a reversal it only matters after an advance.
• Ignoring the body-only rule. The gaps and overlaps are measured on bodies, not full ranges.

References

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

See also

• UpsideGapTwoCrows — the gap-holding sibling.
• Engulfing — stronger two-bar reversal.
• Indicators-Overview — the full taxonomy.