Rate Of Change (ROC) - Built-in Indicator Guide

Calculates the Rate of Change (momentum) of a selected price source over a given period.

Overview

The Rate of Change (ROC) indicator measures the speed of price movement by comparing the current price to a price from a specified number of bars ago. It is a momentum oscillator that helps identify the strength of a trend and potential reversals when it crosses the zero line.

On the chart, a blue ROC line is plotted against a gray zero level. Readings above zero indicate upward momentum, while readings below zero indicate downward momentum. The steepness of the line reflects the acceleration of the move.

How it works

1. The indicator imports the Roc algorithm from indie.algorithms, which encapsulates the ROC calculation.
2. Two parameters are exposed via decorators: length (default 9, minimum 1) and src (default source.CLOSE).
3. A horizontal zero level is drawn with a gray line using the @level decorator.
4. The Main function calls Roc.new(src, length)[0] to compute the ROC value for the current bar.
5. The computed value is returned as a single value, and the @plot.line decorator draws it as a blue line on the chart.

Parameters

Code walkthrough

Imports and algorithm

Lines 1-3 of Rate Of Change.indie5:

# indie:lang_version = 5
from indie import indicator, format, param, source, level, color, plot
from indie.algorithms import Roc

Imports the required decorators and types, along with the Roc algorithm from the standard library. Using a built‑in algorithm keeps the code concise and reliable.

Indicator definition and parameters

Lines 6-9 of Rate Of Change.indie5:

@indicator('ROC', format=format.PRICE)  # Rate Of Change
@param.int('length', default=9, min=1)
@param.source('src', default=source.CLOSE, title='Source')
@level(0, line_color=color.GRAY, title='Zero')

@indicator sets the short name ‘ROC’ and the display format to PRICE, which shows values in the same unit as the source. @param.int and @param.source create user‑adjustable inputs for period length and price source. @level(0) adds a fixed gray zero line for reference.

Plot and main function

Lines 10-12 of Rate Of Change.indie5:

@plot.line(color=color.BLUE, title='ROC')
def Main(self, length, src):
    return Roc.new(src, length)[0]

@plot.line defines a blue line to represent the ROC values. The Main function calls Roc.new(src, length), which returns a series; [0] picks the value for the current bar. The function returns this single value, which is automatically plotted.

Reading the chart

• The blue line represents the ROC value. When it is above the gray zero line, the price source has increased relative to length bars ago; when below, it has decreased.
• The magnitude of the line indicates the strength of the price change. Higher absolute values suggest stronger momentum.
• Crossings of the zero line can be used to identify potential trend changes (bullish when crossing from negative to positive, bearish when crossing from positive to negative).

Implementation notes

• The implementation relies entirely on the built‑in Roc algorithm; no custom math is exposed.
• The indicator does not use any state (MutSeriesF) – the calculation is stateless per bar.
• The format=PRICE means the output is in the same unit as the input price (e.g., dollars, points), not a percentage.
• The indicator does not repaint because Roc.new returns a series and [0] only looks at the current finished bar.

FAQ

What is the default length and can I change it?

The default length is 9. You can change it to any positive integer via the indicator settings in the platform UI.

Does the indicator use the closing price by default?

Yes, the default source is CLOSE. You can change it to other price sources like HIGH, LOW, OPEN, or HL2 via the ‘Source’ parameter.

How do I interpret a negative ROC value?

A negative ROC value means the current price is lower than the price length bars ago, indicating downward momentum. The magnitude gives an idea of the speed of the decline.

Full source code

Indie Script v5, the built-in indicator as shipped with TakeProfit. Add it from the indicators menu or copy the code into the platform’s script editor.

# indie:lang_version = 5
from indie import indicator, format, param, source, level, color, plot
from indie.algorithms import Roc


@indicator('ROC', format=format.PRICE)  # Rate Of Change
@param.int('length', default=9, min=1)
@param.source('src', default=source.CLOSE, title='Source')
@level(0, line_color=color.GRAY, title='Zero')
@plot.line(color=color.BLUE, title='ROC')
def Main(self, length, src):
    return Roc.new(src, length)[0]