wickra/docs/wiki/indicators/volume/Indicator-VolumePriceTrend.md

VolumePriceTrend

Volume-Price Trend (VPT) — a cumulative volume line where each bar's contribution is scaled by its percentage price change.

Quick reference

Field	Value
Family	Volume
Sub-category	Cumulative
Input type	Candle (uses close, volume)
Output type	f64
Output range	unbounded (drifts with cumulative volume)
Default parameters	none (no parameters)
Warmup period	1
Interpretation	Running volume flow; slope and divergence matter.

Formula

VPT_t = VPT_{t−1} + volume_t · (close_t − close_{t−1}) / close_{t−1}

VPT is a close relative of Obv. Where OBV adds the entire bar volume on any up-close, VPT adds volume scaled by the size of the move: a 2 % gain on a given volume moves the line twice as far as a 1 % gain on the same volume. That makes VPT more sensitive to the conviction behind a move. The first bar establishes the baseline at 0.

Parameters

VolumePriceTrend takes no parameters — VolumePriceTrend::new() in Rust, wickra.VolumePriceTrend() in Python, new ta.VolumePriceTrend() in Node.

Inputs / Outputs

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

impl Indicator for VolumePriceTrend {
    type Input = Candle;
    type Output = f64;
    // update(&mut self, input: Candle) -> Option<f64>
}

VolumePriceTrend is a candle-input indicator: it reads close and volume. In Python the streaming update accepts a 6-tuple or a dict; the batch helper takes close and volume numpy arrays. Node and WASM expose update(close, volume) and batch(close, volume).

Warmup

warmup_period() == 1. VPT is cumulative — it emits the baseline 0 from the first candle, then accumulates from the second onward.

Edge cases

• Constant close. With no price change every bar contributes 0, so the line stays flat regardless of volume (constant_close_keeps_line_flat pins this).
• First bar. The first candle has no previous close; VPT emits the baseline 0.0 (emits_from_first_candle_at_zero pins this).
• Zero previous close. A percentage change against a 0.0 prior close is undefined and is treated as 0.
• Candle validation. Candle::new rejects invalid bars upstream.
• Reset. vpt.reset() returns the running total to 0.

Examples

Rust

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

fn main() -> Result<(), Box<dyn std::error::Error>> {
    let mut vpt = VolumePriceTrend::new();
    // closes 10 -> 11 -> 9, volumes 100, 200, 300.
    let out = vpt.batch(&[
        Candle::new(10.0, 10.0, 10.0, 10.0, 100.0, 0)?,
        Candle::new(11.0, 11.0, 11.0, 11.0, 200.0, 1)?,
        Candle::new(9.0, 9.0, 9.0, 9.0, 300.0, 2)?,
    ]);
    println!("{:?}", out);
    Ok(())
}

Output:

[Some(0.0), Some(20.0), Some(-34.54545454545455)]

Bar 1 is the baseline 0. Bar 2 adds 200 · (11−10)/10 = 20. Bar 3 adds 300 · (9−11)/11 = −600/11, leaving 20 − 600/11 ≈ −34.545. This matches the reference_values test in crates/wickra-core/src/indicators/vpt.rs.

Python

import numpy as np
import wickra as ta

vpt = ta.VolumePriceTrend()
close = np.array([10.0, 11.0, 9.0])
volume = np.array([100.0, 200.0, 300.0])
print(vpt.batch(close, volume))

Output:

[  0.          20.         -34.54545455]

Node

const ta = require('wickra');
const vpt = new ta.VolumePriceTrend();
console.log(vpt.batch([10, 11, 9], [100, 200, 300]));

Output:

[ 0, 20, -34.54545454545455 ]

Interpretation

VolumePriceTrend is read like OBV — by slope and by divergence, never by absolute level. A VPT rising in step with price confirms the trend is volume-supported; VPT flattening or falling while price climbs is a bearish divergence warning that the move lacks participation. Versus OBV, VPT gives proportionally more weight to large moves and less to a string of tiny up-closes, so it tracks the magnitude of conviction, not just its direction.

Common pitfalls

• Reading the absolute value. Only slope and divergences carry meaning; the level depends on the stream's start point.
• Expecting OBV-identical behaviour. VPT scales by percentage change, so the two lines diverge — especially across large single-bar moves.

References

The Volume-Price Trend (also "Price-Volume Trend") is a standard cumulative volume study; the volume · ROC accumulation here matches the common definition.

See also

• Indicator-Obv.md — cumulative signed volume, the closest relative.
• Indicator-Adl.md — cumulative range-weighted volume.
• Indicators-Overview.md — the full taxonomy.