Technical indicators

// Average True Range: the Wilder mean of max(high - low, |high - previous close|, |low - previous close|).
// The channel is a moving average of the close, widened by a multiple of the ATR.
indicator "ATR channel"
    edition = 1
    display = price

input length: int = 20, name = "Length", min = 2
input mult: float = 2.0, name = "Multiple", min = 0.1, step = 0.1
let basis = tech.ema(close, length)
let range = tech.atr(length)
let upper = basis + mult * range
let lower = basis - mult * range
plot(upper, name = "Upper", color = color.red)
plot(lower, name = "Lower", color = color.green)
plot(basis, name = "Basis", color = color.gray)

// Bollinger Bands: a simple moving average and bands a number of standard deviations above and below it.
indicator "Bollinger bands"
    edition = 1
    display = price

input length: int = 20, name = "Length", min = 2
input mult: float = 2.0, name = "Deviations", min = 0.1, step = 0.1
let basis = tech.sma(close, length)
let deviation = mult * tech.stdev(close, length)
let upper = basis + deviation
let lower = basis - deviation
let top = plot(upper, name = "Upper", color = color.blue)
let bottom = plot(lower, name = "Lower", color = color.blue)
plot(basis, name = "Basis", color = color.orange)
shade(top, bottom, color = color.fade(color.blue, 92), name = "Band")

// MACD: the difference of a fast and a slow EMA, a signal EMA of that difference, and the gap between them as a histogram.
indicator "MACD"
    edition = 1
    display = pane

input fast_length: int = 12, name = "Fast length", min = 1
input slow_length: int = 26, name = "Slow length", min = 2
input signal_length: int = 9, name = "Signal length", min = 1
let (macd_line, signal_line, hist_value) = tech.macd(
    close,
    fast_length = fast_length,
    slow_length = slow_length,
    signal_length = signal_length,
)
plot(
    hist_value,
    name = "Histogram",
    style = histogram,
    color = if hist_value >= 0 then color.green else color.red,
)
plot(macd_line, name = "MACD", color = color.blue)
plot(signal_line, name = "Signal", color = color.orange)

// Donchian Channel: the highest high and the lowest low of the last `length` bars, and their middle.
indicator "Donchian channel"
    edition = 1
    display = price

input length: int = 20, name = "Length", min = 1
let upper = tech.highest(high, length)
let lower = tech.lowest(low, length)
let middle = (upper + lower) / 2
plot(upper, name = "Upper", color = color.green)
plot(lower, name = "Lower", color = color.red)
plot(middle, name = "Middle", color = color.gray)

// The stochastic oscillator: where the close sits inside the last `length` bars' range, smoothed into %K and %D.
// raw %K = 100 * (close - lowest low) / (highest high - lowest low)
indicator "Stochastic"
    edition = 1
    display = pane

input length: int = 14, name = "Length", min = 1
input smooth: int = 3, name = "Smoothing", min = 1
let lowest_low = tech.lowest(low, length)
let highest_high = tech.highest(high, length)
let raw = 100 * (close - lowest_low) / (highest_high - lowest_low)
let k = tech.sma(raw, smooth)
let d = tech.sma(k, smooth)
plot(k, name = "%K", color = color.blue)
plot(d, name = "%D", color = color.orange)
level(80, name = "Upper", color = color.gray, style = dashed)
level(20, name = "Lower", color = color.gray, style = dashed)

// Average Directional Index: how strong a trend is, whichever way it points, with the two directional indicators.
indicator "ADX"
    edition = 1
    display = pane

input di_length: int = 14, name = "DI length", min = 1
input adx_length: int = 14, name = "ADX smoothing", min = 1
let (plus, minus, adx) = tech.dmi(di_length, adx_length)
plot(adx, name = "ADX", color = color.black, width = 2)
plot(plus, name = "Plus DI", color = color.green)
plot(minus, name = "Minus DI", color = color.red)
level(25, name = "Trend", color = color.gray, style = dashed)

// On-Balance Volume: add the volume on an up close, subtract it on a down close, and smooth the running total.
indicator "On-balance volume"
    edition = 1
    display = pane

input length: int = 20, name = "Signal length", min = 1
let direction = math.sign(close - close[1])
let obv = tech.cum_sum(direction * volume)
plot(obv, name = "OBV", color = color.blue)
plot(tech.ema(obv, length), name = "Signal", color = color.orange)