LongLine

A single candle whose range is longer than the recent average and whose body dominates that range — a solid directional bar. Because "long" only has meaning relative to recent activity, the detector compares each candle's range against a rolling average of the previous period ranges.

Quick reference

Field	Value
Family	Candlestick Patterns
Input type	Candle
Output type	f64 — +1.0 long white, -1.0 long black, 0.0 otherwise
Output range	{-1.0, 0.0, +1.0}
Default parameters	period = 5
Warmup period	period (default 5)
Interpretation	A conviction bar relative to recent ranges

Formula

avg = mean range of the previous `period` candles
long line = range > avg  AND  |close − open| >= 0.5 · range
white -> +1.0,  black -> -1.0

This rolling baseline is the one place the candlestick family departs from a purely intra-candle rule, since a long/short classification is inherently scale-relative. See crates/wickra-core/src/indicators/long_line.rs.

Parameters

Name	Type	Default	Valid range	Source
period	usize	5	>= 1	LongLine::with_period (long_line.rs)

with_period(0) errors (rejects_zero_period, accepts_valid_period). LongLine::new() uses the default period; Python/Node construct with the default.

Signed ±1 encoding

Emits the uniform candlestick sign convention — +1.0 long white, −1.0 long black, 0.0 no pattern — a single feature-matrix dimension.

Inputs / Outputs

use wickra::{Indicator, LongLine, Candle};
// LongLine: Input = Candle, Output = f64
const _: fn(&mut LongLine, Candle) -> Option<f64> = <LongLine 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 while the rolling average fills).

Warmup

warmup_period() == period (default 5). The first period candles return 0.0 while the rolling average fills (warmup_returns_zero, accessors_and_metadata).

Edge cases

• Short range. A range at or below the rolling average yields 0.0 (short_range_yields_zero).
• Wide range, small body. A long range with an indecisive body yields 0.0 (wide_range_small_body_yields_zero).
• Reset. reset() clears the rolling-range buffer and restarts warmup (reset_clears_state).

Examples

Rust

use wickra::{BatchExt, Candle, Indicator, LongLine};

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Five small bars (range 1.0) establish the baseline, then one long white bar.
    let mut bars: Vec<Candle> = (0..5)
        .map(|i| Candle::new(10.0, 10.5, 9.5, 10.1, 1.0, i).unwrap())
        .collect();
    bars.push(Candle::new(10.0, 13.0, 9.9, 12.9, 1.0, 5)?); // range 3.1, white
    let mut t = LongLine::new();
    println!("{:?}", t.batch(&bars));
    Ok(())
}

Output:

[Some(0.0), Some(0.0), Some(0.0), Some(0.0), Some(0.0), Some(1.0)]

The sixth bar's range 3.1 beats the 1.0 baseline and its body dominates — a long white line. This matches the long_white_line_is_plus_one unit test.

Python

import numpy as np
import wickra as ta

o = np.array([10.0]*5 + [10.0])
h = np.array([10.5]*5 + [13.0])
l = np.array([9.5]*5  + [9.9])
c = np.array([10.1]*5 + [12.9])

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

Node

const ta = require('wickra');
const t = new ta.LongLine();
for (let i = 0; i < 5; i++) t.update(10, 10.5, 9.5, 10.1);
console.log(t.update(10, 13, 9.9, 12.9)); // 1

Streaming

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

let mut t = LongLine::new();
let candle_stream: Vec<wickra::Candle> = Vec::new(); // your live OHLCV candle feed
for bar in candle_stream {
    match t.update(bar) {
        Some(1.0)  => { /* strong white bar relative to recent ranges */ }
        Some(-1.0) => { /* strong black bar */ }
        _ => {}
    }
}

Interpretation

1. Conviction, in context. A bar that is long relative to its neighbours marks a decisive push — more informative than an absolute size threshold.
2. Tune the window. A longer period smooths the baseline (fewer, higher- conviction signals); a shorter one reacts faster.
3. Direction = colour. White is bullish conviction, black bearish.

Common pitfalls

• Absolute thinking. A bar that looks big on the chart may be ordinary relative to recent ranges — and vice versa.
• Small body. A wide range with a small body is indecision, not a long line.

References

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

See also

• ShortLine — the compact counterpart.
• Marubozu — the shadowless full-body bar.
• Indicators-Overview — the full taxonomy.