Choppiness Index (True Range Box) (CHOPTR)

Summary

Choppiness Index with a true-range box: the true range travelled over a window against the span from its highest true high to its lowest true low. Bill Dreiss's form as published in 1993. Log-scaled so that a straight run reads 0 and bars that each fill the whole box read 100. Measures whether the market is trending, not in which direction: low values mean a directional run, high values sideways chop.

Chart

Reference data (CSV) · Chart (SVG)

Chart metadata i

Outputs

• outReal: line · zero · positive

Formula

TH[j] = max(High[j], Close[j-1]) and TL[j] = min(Low[j], Close[j-1]), the true high and true low. TR[j] = TH[j] - TL[j].

S = SUM( TR[j] ) and R = MAX( TH[j] ) - MIN( TL[j] ), both over j = t-optInTimePeriod+1 .. t.

CHOPTR = 100 * log10( S / R ) / log10( optInTimePeriod ).

The first true range reads the close one bar before the window, so the first value needs optInTimePeriod + 1 bars.

Notes

• The box reaches the close just before each bar. Most charting platforms instead use the window's highest high minus its lowest low; that form is CHOP. The two differ only on bars where the close before the window lies outside the window's high-low range: a gap into the window.
• With every close inside its own bar's high-low range, the value stays within 0 to 100, up to rounding.
• A window with no true range reports 100.
• Dreiss's 3-bar smoothing of the index is not built in; apply a moving average to outReal to obtain it.

Inputs

• inHigh — High price of each bar
• inLow — Low price of each bar
• inClose — Close price of each bar

Outputs

• outReal — Choppiness Index value

Parameters

Parameter	Type	Default	Accepted values	Description
optInTimePeriod	integer	14	2–100000	Number of bars in the window

Properties

Numerical Stability: Start-Independent

☐ Overlap Input
✅ Independent Y-Axis i
☐ Candlestick
☐ Display Shift

☐ Can Output NaN or ±Inf
☐ Identity at Period 1
✅ Uses Transcendental i
☐ Input Must Be Positive

Example

C

#include <stdio.h>
#include <ta_libc.h>

int n = 252;
double high[252]; /* your data, oldest first */
double low[252]; /* your data, oldest first */
double close[252]; /* your data, oldest first */
double out[252];
int outBegIdx, outNBElement;

TA_Initialize();
TA_CHOPTR( 0, n - 1, high, low, close, 14, &outBegIdx, &outNBElement, out );
printf( "%d values from bar %d; last out = %f\n", outNBElement, outBegIdx, out[outNBElement - 1] );

Rust

use ta_lib::Core;

let high = vec![0.0; 252]; // your data, oldest first
let low = vec![0.0; 252]; // your data, oldest first
let close = vec![0.0; 252]; // your data, oldest first
let mut out = vec![0.0; 252];

let core = Core::new();
let range = core.choptr(0, high.len() - 1, &high, &low, &close, 14, &mut out)?;
println!("{} values from bar {}; last out = {}", range.count, range.beg_idx, out[range.count - 1]);

Java

import io.github.talib.Core;
import io.github.talib.OutRange;

double[] high = new double[252]; // your data, oldest first
double[] low = new double[252]; // your data, oldest first
double[] close = new double[252]; // your data, oldest first
double[] out = new double[252];

Core core = Core.DEFAULT;
OutRange r = core.choptr(0, high.length - 1, high, low, close, 14, out);
System.out.println(r.count() + " values from bar " + r.begIdx() + "; last out = " + out[r.count() - 1]);

C#

using System;
using TALib;

var high = new double[252]; // your data, oldest first
var low = new double[252]; // your data, oldest first
var close = new double[252]; // your data, oldest first
var outReal = new double[252];

var core = Core.Default;
OutRange r = core.Choptr(0, high.Length - 1, high, low, close, 14, outReal);
Console.WriteLine($"{r.Count} values from bar {r.BegIdx}; last outReal = {outReal[r.Count - 1]}");

TypeScript

import { choptr } from 'ta-lib';

const high = new Float64Array(252); // your data, oldest first
const low = new Float64Array(252); // your data, oldest first
const close = new Float64Array(252); // your data, oldest first

const { begIdx, values } = choptr({ high, low, close }, { timePeriod: 14 });
console.log(values.length + ' values from bar ' + begIdx + '; last values = ' + values[values.length - 1]);

Implementation

Added in 0.8.3 (ta-lib-python 0.8.3).

TA-Lib Definition: choptr.c · choptr.yaml

Native	File
C	ta_CHOPTR.c
Rust	choptr.rs
Java	Core_CHOPTR.java
C#	Core_CHOPTR.cs
TypeScript	choptr.ts

Python: talib.CHOPTR (ta-lib-python 0.8.3 or later), see ta-lib-python.

TA-Lib is also available for R and more using a wrapper.

Aliases

Choppiness Index, Dreiss Choppiness Index, True Range Choppiness Index

See Also

CHOP · VHF · ADX · TRANGE

References

• Gibbons Burke, "Measuring market choppiness with chaos", Futures, October 1993, pp. 52-53
• Incredible Charts: Choppiness Index