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//! Kicking-by-Length candlestick pattern.
use crate::ohlcv::Candle;
use crate::traits::Indicator;
/// Kicking-by-Length — the [`Kicking`](crate::Kicking) pattern with the signal
/// taken from the *longer* of the two marubozu rather than from the gap direction.
/// When the two shadowless candles differ in size, the bigger one is treated as
/// the dominant force.
///
/// ```text
/// marubozu = |close − open| >= 0.95 * (high − low)
/// setup: two opposite-coloured marubozu separated by a gap
/// black then white gapping UP, or white then black gapping DOWN
/// signal = colour of the LONGER marubozu (white -> +1.0, black -> −1.0)
/// ```
///
/// Output is `+1.0` or `−1.0` when the kicking setup is present and `0.0`
/// otherwise. Note this can disagree with [`Kicking`](crate::Kicking): a black
/// marubozu kicked up by a *shorter* white marubozu reports `−1.0` here. The first
/// bar always returns `0.0` because the two-bar window is not yet filled. The
/// marubozu threshold follows the geometric house style rather than TA-Lib's
/// rolling averages. Pattern-shape check only — no trend filter is applied;
/// combine with a trend indicator for actionable signals.
///
/// # Signed ±1 encoding
///
/// This detector emits the uniform candlestick sign convention shared across the
/// pattern family — `+1.0` bullish, `−1.0` bearish, `0.0` no pattern — so it
/// drops straight into a machine-learning feature matrix as a single dimension.
///
/// # Example
///
/// ```
/// use wickra_core::{Candle, Indicator, KickingByLength};
///
/// let mut indicator = KickingByLength::new();
/// indicator.update(Candle::new(12.0, 12.0, 10.0, 10.0, 1.0, 0).unwrap());
/// // White marubozu gaps up and is the longer body -> +1.
/// let out = indicator
/// .update(Candle::new(14.0, 20.0, 14.0, 20.0, 1.0, 1).unwrap());
/// assert_eq!(out, Some(1.0));
/// ```
#[derive(Debug, Clone, Default)]
pub struct KickingByLength {
prev: Option<Candle>,
has_emitted: bool,
}
impl KickingByLength {
/// Construct a new Kicking-by-Length detector.
pub const fn new() -> Self {
Self {
prev: None,
has_emitted: false,
}
}
}
fn is_marubozu(candle: &Candle) -> bool {
let range = candle.high - candle.low;
range > 0.0 && (candle.close - candle.open).abs() >= 0.95 * range
}
impl Indicator for KickingByLength {
type Input = Candle;
type Output = f64;
fn update(&mut self, candle: Candle) -> Option<f64> {
self.has_emitted = true;
let prev = self.prev;
self.prev = Some(candle);
let Some(bar1) = prev else {
return Some(0.0);
};
if !is_marubozu(&bar1) || !is_marubozu(&candle) {
return Some(0.0);
}
let body1 = bar1.close - bar1.open;
let body2 = candle.close - candle.open;
let bullish_setup = body1 < 0.0 && body2 > 0.0 && candle.low > bar1.high;
let bearish_setup = body1 > 0.0 && body2 < 0.0 && candle.high < bar1.low;
if !(bullish_setup || bearish_setup) {
return Some(0.0);
}
// The longer marubozu's colour is the signal.
let longer_is_white = if body1.abs() >= body2.abs() {
body1 > 0.0
} else {
body2 > 0.0
};
Some(if longer_is_white { 1.0 } else { -1.0 })
}
fn reset(&mut self) {
self.prev = None;
self.has_emitted = false;
}
fn warmup_period(&self) -> usize {
2
}
fn is_ready(&self) -> bool {
self.has_emitted
}
fn name(&self) -> &'static str {
"KickingByLength"
}
}
#[cfg(test)]
mod tests {
use super::*;
use crate::traits::BatchExt;
fn c(open: f64, high: f64, low: f64, close: f64, ts: i64) -> Candle {
Candle::new(open, high, low, close, 1.0, ts).unwrap()
}
#[test]
fn accessors_and_metadata() {
let t = KickingByLength::new();
assert_eq!(t.name(), "KickingByLength");
assert_eq!(t.warmup_period(), 2);
assert!(!t.is_ready());
}
#[test]
fn longer_white_is_plus_one() {
let mut t = KickingByLength::new();
assert_eq!(t.update(c(12.0, 12.0, 10.0, 10.0, 0)), Some(0.0));
// White marubozu (length 6) longer than the black one (length 2).
assert_eq!(t.update(c(14.0, 20.0, 14.0, 20.0, 1)), Some(1.0));
}
#[test]
fn longer_black_is_minus_one() {
let mut t = KickingByLength::new();
// Black marubozu (length 6), then a shorter white marubozu (length 2)
// gapping up -> the longer black body wins, so -1.
assert_eq!(t.update(c(16.0, 16.0, 10.0, 10.0, 0)), Some(0.0));
assert_eq!(t.update(c(18.0, 20.0, 18.0, 20.0, 1)), Some(-1.0));
}
#[test]
fn not_marubozu_yields_zero() {
let mut t = KickingByLength::new();
t.update(c(12.0, 14.0, 8.0, 10.0, 0));
assert_eq!(t.update(c(14.0, 20.0, 14.0, 20.0, 1)), Some(0.0));
}
#[test]
fn no_gap_yields_zero() {
let mut t = KickingByLength::new();
t.update(c(12.0, 12.0, 10.0, 10.0, 0));
assert_eq!(t.update(c(11.0, 13.0, 11.0, 13.0, 1)), Some(0.0));
}
#[test]
fn first_bar_returns_zero() {
let mut t = KickingByLength::new();
assert_eq!(t.update(c(12.0, 12.0, 10.0, 10.0, 0)), Some(0.0));
}
#[test]
fn batch_equals_streaming() {
let candles: Vec<Candle> = (0..40)
.map(|i| {
let base = 100.0 + i as f64 * 5.0;
if i % 2 == 0 {
c(base + 2.0, base + 2.0, base, base, i)
} else {
c(base + 3.0, base + 5.0, base + 3.0, base + 5.0, i)
}
})
.collect();
let mut a = KickingByLength::new();
let mut b = KickingByLength::new();
assert_eq!(
a.batch(&candles),
candles.iter().map(|x| b.update(*x)).collect::<Vec<_>>()
);
}
#[test]
fn reset_clears_state() {
let mut t = KickingByLength::new();
t.update(c(12.0, 12.0, 10.0, 10.0, 0));
t.update(c(14.0, 20.0, 14.0, 20.0, 1));
assert!(t.is_ready());
t.reset();
assert!(!t.is_ready());
assert_eq!(t.update(c(12.0, 12.0, 10.0, 10.0, 0)), Some(0.0));
}
}