Three Drives

A symmetric harmonic of three drives separated by two retracements, read from the last seven pivots. Three rising drives → bearish -1; three falling drives → bullish +1.

Quick reference

Item	Value
Family	Harmonic Patterns
Input type	Candle (uses high, low)
Output type	f64 (+1 / -1 / 0)
Output range	{-1.0, 0.0, +1.0}
Default parameters	none (swing threshold 5%, baked)
Warmup period	8
Interpretation	Exhaustion after three symmetric drives

Formula

last seven pivots, six alternating legs R1 D1 R2 D2 R3 D3:
  D1 / R1 ∈ [1.13, 1.75]        (each drive extends the leg before it)
  D2 / R2 ∈ [1.13, 1.75]
  D3 / R3 ∈ [1.13, 1.75]
  D1 ≈ D2 ≈ D3 (within 20%)     (the three drives are similar in size)
  R1 ≈ R2 ≈ R3 (within 30%)     (the retracements between them are similar)
direction: terminal pivot a swing high → -1 (drives up), a swing low → +1

See crates/wickra-core/src/indicators/three_drives.rs.

Parameters

None. Swing threshold 0.05 is a baked-in family constant (pattern_swing.rs); the extension windows and symmetry tolerances are documented detector constants. ThreeDrives::new is infallible.

Inputs / Outputs

const _: fn(&mut wickra::ThreeDrives, wickra::Candle) -> Option<f64> =
    <wickra::ThreeDrives as wickra::Indicator>::update;

• Python. update((o,h,l,c,v,ts)) → float (never None); batch(open, high, low, close) → array.array('d').
• Node. update(open, high, low, close) → number; batch(open, high, low, close) → number[].
• WASM. update(open, high, low, close) → number.

Warmup

warmup_period() == 8. Seven confirmed pivots are required — a structure that stops after two drives is incomplete, not a match, and the detector keeps returning None. Pinned by tests accessors_and_metadata and two_drives_alone_do_not_complete_the_pattern.

Edge cases

• Three rising drives report -1 (test bearish_three_drives_is_minus_one).
• Three falling drives report +1 (test bullish_three_drives_is_plus_one).
• Asymmetric / non-extending drives report 0.0 (test asymmetric_drives_do_not_trigger).
• reset clears state (test reset_clears_state).
• Streaming equals batch (test batch_equals_streaming).

Examples

Rust

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

fn main() -> Result<(), Box<dyn std::error::Error>> {
    // Three rising drives (124, 128, 132), each extending a 10-point
    // retracement by 14 → bearish exhaustion.
    let bars = [
        (119.88, 120.0, 119.88, 119.88),
        (110.0, 118.8, 110.0, 110.0),
        (111.1, 124.0, 111.1, 111.1),
        (114.0, 122.76, 114.0, 114.0),
        (115.14, 128.0, 115.14, 115.14),
        (118.0, 126.72, 118.0, 118.0),
        (119.18, 132.0, 119.18, 119.18),
        (118.8, 130.68, 118.8, 118.8), // third drive confirms → bearish
    ];
    let mut pat = ThreeDrives::new();
    let mut last = 0.0;
    for (ts, (o, h, l, c)) in bars.iter().enumerate() {
        last = pat
            .update(Candle::new(*o, *h, *l, *c, 1.0, ts as i64)?)
            .unwrap_or(last);
    }
    println!("{last}"); // -1
    Ok(())
}

Python

import wickra as ta

bars = [
    (119.88, 120.0, 119.88, 119.88, 1.0, 0),
    (110.0, 118.8, 110.0, 110.0, 1.0, 1),
    (111.1, 124.0, 111.1, 111.1, 1.0, 2),
    (114.0, 122.76, 114.0, 114.0, 1.0, 3),
    (115.14, 128.0, 115.14, 115.14, 1.0, 4),
    (118.0, 126.72, 118.0, 118.0, 1.0, 5),
    (119.18, 132.0, 119.18, 119.18, 1.0, 6),
    (118.8, 130.68, 118.8, 118.8, 1.0, 7),
]
pat = ta.ThreeDrives()
print([pat.update(b) for b in bars][-1])  # -1.0

Node

const wickra = require('wickra');
const bars = [
  [119.88, 120.0, 119.88, 119.88], [110.0, 118.8, 110.0, 110.0],
  [111.1, 124.0, 111.1, 111.1], [114.0, 122.76, 114.0, 114.0],
  [115.14, 128.0, 115.14, 115.14], [118.0, 126.72, 118.0, 118.0],
  [119.18, 132.0, 119.18, 119.18], [118.8, 130.68, 118.8, 118.8],
];
const pat = new wickra.ThreeDrives();
let last = 0;
for (const [o, h, l, c] of bars) last = pat.update(o, h, l, c);
console.log(last); // -1

Streaming

pat = ta.ThreeDrives()
for o, h, l, c, v, ts in candle_feed:
    signal = pat.update((o, h, l, c, v, ts))
    if signal < 0:
        pass  # three drives up — exhaustion, reversal lower
    elif signal > 0:
        pass  # three drives down — exhaustion, reversal higher

Interpretation

1. Symmetric exhaustion. Three measured, equal drives with equal pullbacks signal that the move is overextended; the reversal target is back toward the pattern's origin.
2. Symmetry is the filter. The two ≈ checks (equal drives, equal retracements) keep ragged, accidental three-leg moves out.

Common pitfalls

• Two-drive reading. This detector keys on the two visible drive legs of the five-pivot window; ensure the data actually shows the classic three-push structure before trusting the signal.
• Confirmation lag. Non-repainting but lags the third drive's extreme.

References

• Pesavento, L. Fibonacci Ratios with Pattern Recognition (1997).

See also

• Gartley, Crab.
• Indicators-Overview — full taxonomy.