Stochastic RSI (Stoch RSI) - Built-in Indicator Guide

Computes Stochastic RSI: RSI of the source, converted to a stochastic oscillator, with smoothed K and D lines.

Overview

Stochastic RSI applies the stochastic formula to RSI values instead of price. It measures where the current RSI level sits inside its own recent high-low range over the chosen stochastic length, then smooths the result to produce K and D lines.

The chart shows a blue K line and a red D line. A light background band marks the 20 and 80 levels, and a gray line marks the 50 level. These visual guides help read the oscillator in the context of its extremes.

How it works

1. Compute the RSI series from the selected source with rsi_length.
2. Pass the same RSI series as high, low, and close inputs to Stoch.new to build the stochastic of RSI over k_length bars.
3. Apply a simple moving average with period k_smoothing to the stochastic value to produce the fast K line.
4. Apply a simple moving average with period d_smoothing to the K series to produce the slow D line.
5. Return k[0] and d[0] so the current bar values are plotted by the two @plot.line decorators.
6. The 20/80 band and 50 middle level are drawn from the @band and @level decorators.

Mathematical model

Parameters

Code walkthrough

Indicator metadata and UI inputs

Lines 6-11 of Stochastic RSI.indie5:

@indicator('Stoch RSI', format=format.PRICE)  # Stochastic RSI
@param.int('k_smoothing', default=3, min=1, title='Fast K stochastic smoothing')
@param.int('d_smoothing', default=3, min=1, title='Slow D stochastic smoothing')
@param.int('rsi_length', default=14, min=1, title='RSI length')
@param.int('k_length', default=14, min=1, title='Stochastic Length')
@param.source('src', default=source.CLOSE, title='Source')

The decorators define everything the chart needs to render the indicator and expose settings. @param.int and @param.source create configuration controls.

Computing RSI and the stochastic value

Lines 16-18 of Stochastic RSI.indie5:

def Main(self, k_smoothing, d_smoothing, rsi_length, k_length, src):
    rsi = Rsi.new(src, rsi_length)
    k = Sma.new(Stoch.new(rsi, rsi, rsi, k_length), k_smoothing)

Inside Main, Rsi.new returns a series based on the selected source. That series is then passed to Stoch.new as high, low, and close, so the stochastic is calculated entirely from RSI values. The result is smoothed with Sma.new to form the fast K series.

Smoothing D and returning plotted values

Lines 19-20 of Stochastic RSI.indie5:

    d = Sma.new(k, d_smoothing)
    return k[0], d[0]

The D line is a second simple moving average applied to the K series. The return tuple (k[0], d[0]) supplies the current bar values for the two plot lines, in the same order as the @plot.line decorators: K is blue and D is red.

Reading the chart

• The blue K line is the smoothed stochastic of RSI; the red D line is the smoothed version of K.
• Values above 80 or below 20 are plotted outside the shaded band region, indicating oscillator extremes relative to the configured band.
• The 50 gray line separates the upper and lower halves of the oscillator range.
• Because K is smoothed once and D is smoothed twice, D generally reacts more slowly than K.

Implementation notes

• The Stoch.new call receives the same rsi series for its high, low, and close parameters, so the stochastic range is based on RSI levels, not on price.
• All computed objects are stateful series. k[0] and d[0] are the current bar values; previous-bar values would be accessed with k[1] and d[1].
• Every @param.int field has a minimum of 1, so the generated settings UI will not accept zero or negative periods.
• The return tuple order matches the two @plot.line decorators: first value is blue K, second is red D.

FAQ

What do k_smoothing and d_smoothing control?

k_smoothing is the period of the SMA applied to the stochastic of RSI to produce the K line. d_smoothing is the period of the SMA applied to K to produce the D line.

Can I change the input source?

Yes, the src parameter defaults to source.CLOSE and is exposed through @param.source, so you can select another supported source in the indicator settings.

What do the horizontal levels on the chart mean?

The 20 and 80 values draw the background band defined by @band, and the 50 line is a middle level defined by @level. They are guides for reading the oscillator’s position and extremes.

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, band, color, level, plot
from indie.algorithms import Rsi, Stoch, Sma


@indicator('Stoch RSI', format=format.PRICE)  # Stochastic RSI
@param.int('k_smoothing', default=3, min=1, title='Fast K stochastic smoothing')
@param.int('d_smoothing', default=3, min=1, title='Slow D stochastic smoothing')
@param.int('rsi_length', default=14, min=1, title='RSI length')
@param.int('k_length', default=14, min=1, title='Stochastic Length')
@param.source('src', default=source.CLOSE, title='Source')
@band(20, 80, fill_color=color.AQUA(0.1), line_color=color.GRAY, title='Background')
@level(50, line_color=color.GRAY(0.5), title='Middle Band')
@plot.line(color=color.BLUE, title='K')
@plot.line(color=color.RED, title='D')
def Main(self, k_smoothing, d_smoothing, rsi_length, k_length, src):
    rsi = Rsi.new(src, rsi_length)
    k = Sma.new(Stoch.new(rsi, rsi, rsi, k_length), k_smoothing)
    d = Sma.new(k, d_smoothing)
    return k[0], d[0]