Equivolume

Richard Arms' Equivolume chart as numbers — each bar is a box whose height is its price range and whose width is its volume relative to the recent average.

Quick reference

Field	Value
Family	Ichimoku & Charts
Input type	Candle (high / low / volume)
Output type	EquivolumeOutput { height, width }
Output range	height ≥ 0 (price units); width ≥ 0 (1.0 = average volume)
Default parameters	(period = 14) (Python)
Warmup period	period
Interpretation	Tall+narrow = easy move; short+wide = churn (S/R).

Formula

height = high − low
width  = volume / SMA(volume, period)        (1.0 = average volume)

Equivolume substitutes volume for the time axis. A tall narrow box (big range, light volume) is an easy move; a short wide box (small range, heavy volume) is churn that often marks support/resistance. Reporting both dimensions lets you reconstruct that shape — the height/width relationship is Arms' ease-of-movement read. Source: crates/wickra-core/src/indicators/equivolume.rs.

Parameters

Name	Type	Default	Valid range	Source	Description
period	usize	14 (Python)	>= 1	equivolume.rs:56	Volume-averaging window for the box width. 0 errors with Error::PeriodZero.

The period getter returns the window; value returns the current box if ready.

Inputs / Outputs

From crates/wickra-core/src/indicators/equivolume.rs:

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

A Candle in, an Option<EquivolumeOutput> out. The Python binding returns a (height, width) tuple from update and an (n, 2) array from batch(high, low, volume); Node returns { height, width } and a flat Float64Array of length n*2; WASM mirrors the object with camelCase keys.

Warmup

warmup_period() == period. The volume SMA seeds before the first box (first_emission_at_warmup_period pins this).

Edge cases

• Height = range. height equals high − low (height_is_range pins this).
• Average width = 1. Average volume gives width == 1 (average_volume_width_is_one pins this).
• Heavy bar wide. Above-average volume gives width > 1 (heavy_bar_is_wide pins this).
• Finiteness. Candle::new rejects non-finite fields, so no in-method guard is needed.
• Reset. e.reset() clears the volume SMA and the last value (reset_clears_state).

Examples

Rust

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

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut e = Equivolume::new(3)?;
    let c = |vol: f64| Candle::new(98.0, 102.0, 98.0, 100.0, vol, 0).unwrap();
    let out = e.batch(&[c(1_000.0), c(1_000.0), c(4_000.0)]).last().unwrap().unwrap();
    println!("height={} width={}", out.height, out.width); // 4, >1 (heavy)
    Ok(())
}

Python

import numpy as np
import wickra as ta

e = ta.Equivolume(14)
high = ...; low = ...; volume = ...
height, width = e.batch(high, low, volume).T

Node

const ta = require('wickra');

const e = new ta.Equivolume(14);
console.log('warmupPeriod:', e.warmupPeriod()); // 14

Streaming

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

let mut e = Equivolume::new(14).unwrap();
let feed: Vec<Candle> = Vec::new(); // your live stream
for candle in feed {
    if let Some(box_) = e.update(candle) {
        let ease = box_.height / box_.width.max(1e-9); // tall/narrow -> high
    }
}

Streaming update and batch are equivalent tick-for-tick (batch_equals_streaming pins this).

Interpretation

1. Ease of movement. Tall, narrow boxes (high height/width) confirm a strong, unopposed move; the opposite warns of resistance.
2. Breakout quality. A wide box on a breakout means heavy participation — stronger than a narrow one.
3. Power boxes. A box both taller and wider than its neighbours (Arms' "power box") signals a decisive, high-conviction bar.

Common pitfalls

• Needs real volume. Width is meaningless on synthetic volume.
• Not a signal. Equivolume is descriptive; combine the shape with price structure.
• Range, not body. Height uses the high-low range; for the body version see CandleVolume.

References

Arms, R. W. (1971), Profits in Volume: Equivolume Charting.

See also

• Indicator-CandleVolume — the candlestick (body) variant.
• Indicator-EaseOfMovement — Arms' EMV oscillator.
• Indicator-BetterVolume — VSA effort-vs-result.
• Indicators-Overview — the full taxonomy.