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Custom Functions in Pine Script

4 min read

Custom Functions in Pine Script

Custom functions help you write cleaner, reusable code. This guide covers function creation and best practices.

Why Use Functions?

BenefitDescription
ReusabilityWrite once, use many times
ReadabilityCleaner, organized code
MaintainabilityChange in one place
ComplexityBreak down complex logic

Basic Functions

Simple Function

//@version=6
indicator("Simple Function")
 
// Function to calculate average
myAverage(a, b) =>
    (a + b) / 2
 
avg = myAverage(10, 20)
plot(avg)

Function with Multiple Returns

//@version=6
indicator("Multi Return")
 
// Return multiple values
getRange(highPrice, lowPrice) =>
    range = highPrice - lowPrice
    midpoint = (highPrice + lowPrice) / 2
    [range, midpoint]
 
[rng, mid] = getRange(high, low)
 
plot(rng, title="Range")
plot(mid, title="Midpoint")

Practical Functions

Moving Average Function

//@version=6
indicator("MA Function")
 
// Custom MA function
calculateMA(source, length, type) =>
    if type == "SMA"
        ta.sma(source, length)
    else if type == "EMA"
        ta.ema(source, length)
    else if type == "WMA"
        ta.wma(source, length)
    else
        ta.rma(source, length)
 
// Use the function
maSMA = calculateMA(close, 20, "SMA")
maEMA = calculateMA(close, 20, "EMA")
 
plot(maSMA, color=color.blue)
plot(maEMA, color=color.red)

Signal Function

//@version=6
indicator("Signal Function")
 
// Generate signals
getSignals(maFast, maSlow) =>
    longSignal = ta.crossover(maFast, maSlow)
    shortSignal = ta.crossunder(maFast, maSlow)
    [longSignal, shortSignal]
 
fast = ta.ema(close, 12)
slow = ta.ema(close, 26)
 
[buy, sell] = getSignals(fast, slow)
 
plotshape(buy, location=location.belowbar, style=shape.labelup, color=color.lime)
plotshape(sell, location=location.abovebar, style=shape.labeldown, color=color.red)
 
plot(fast, color=color.green)
plot(slow, color=color.red)

Stop Loss Function

//@version=6
indicator("SL Function")
 
// Calculate ATR-based stop
calculateStop(entryPrice, atr, multiplier, isLong) =>
    if isLong
        entryPrice - atr * multiplier
    else
        entryPrice + atr * multiplier
 
atr = ta.atr(14)
 
// Long stop
longStop = calculateStop(close, atr, 2, true)
 
// Short stop
shortStop = calculateStop(close, atr, 2, false)
 
plot(longStop, color=color.red)
plot(shortStop, color=color.green)

Helper Functions

Color Functions

//@version=6
indicator("Color Helper")
 
// Color based on condition
getTrendColor(price, ma) =>
    price > ma ? color.green : color.red
 
ma = ta.sma(close, 20)
trendColor = getTrendColor(close, ma)
 
plot(ma, color=trendColor, linewidth=2)

Price Functions

//@version=6
indicator("Price Helpers")
 
// Get price change
priceChange(current, previous) =>
    current - previous
 
// Get percent change  
percentChange(current, previous) =>
    ((current - previous) / previous) * 100
 
change = priceChange(close, close[1])
pctChange = percentChange(close, close[1])
 
plot(change, title="Change")
plot(pctChange, title="% Change")

Indicator Functions

//@version=6
indicator("Indicator Helpers")
 
// Combined RSI
getRSISignal(length, overbought, oversold) =>
    rsi = ta.rsi(close, length)
    signal = rsi < oversold ? "BUY" : rsi > overbought ? "SELL" : "NEUTRAL"
    [rsi, signal]
 
[rsiVal, signal] = getRSISignal(14, 70, 30)
 
plot(rsiVal, title="RSI")
hline(70)
hline(30)

Library Functions

Create Indicator Library

//@version=6
indicator("Indicator Library", overlay=true)
 
// === MA Library ===
ma(source, length, type) =>
    switch type
        "SMA" => ta.sma(source, length)
        "EMA" => ta.ema(source, length)
        "WMA" => ta.wma(source, length)
        "VWMA" => ta.vwma(source, length)
        => ta.rma(source, length)
 
// === Signal Library ===
crossSignal(series1, series2) =>
    [ta.crossover(series1, series2), ta.crossunder(series1, series2)]
 
// === Volatility Library ===
volatility(length) =>
    atr = ta.atr(length)
    avg = ta.sma(atr, length)
    atr > avg * 1.5
 
// === Use Library ===
sma20 = ma(close, 20, "SMA")
ema20 = ma(close, 20, "EMA")
 
[crossUp, crossDown] = crossSignal(sma20, ema20)
vol = volatility(14)
 
plot(sma20)
plot(ema20)
plotshape(crossUp, location=location.belowbar, style=shape.arrowup, color=color.lime)
plotshape(crossDown, location=location.abovebar, style=shape.arrowdown, color=color.red)

Advanced Functions

Recursive Functions

//@version=6
indicator("Recursive")
 
// Calculate cumulative sum
cumulativeSum(series, length) =>
    sum = 0.0
    for i = 0 to length - 1
        sum := sum + series[i]
    sum
 
cumSum = cumulativeSum(close, 20)
plot(cumSum)

Array-Based Functions

//@version=6
indicator("Array Function")
 
// Find highest in array
findHighest(src, length) =>
    arr = array.new_float(0)
    for i = 0 to length - 1
        array.push(arr, src[i])
    array.max(arr)
 
highest = findHighest(high, 20)
plot(highest)

Conditional Functions

//@version=6
indicator("Conditional Function")
 
// Dynamic MA type
getDynamicMA(price, volatility) =>
    length = volatility > ta.atr(14) * 2 ? 50 : 20
    ta.ema(price, length)
 
vol = ta.atr(14)
dynamicMA = getDynamicMA(close, vol)
 
plot(dynamicMA)

Complete Example

//@version=6
indicator("Complete Functions", overlay=true)
 
// === INPUTS ===
maType = input.string("EMA", "MA Type", options=["SMA", "EMA", "WMA"])
maLength = input.int(20, "MA Length")
atrLength = input.int(14, "ATR")
atrMultiplier = input.float(2.0, "ATR Multiplier")
 
// === FUNCTIONS ===
 
// MA function
ma(src, len, type) =>
    switch type
        "SMA" => ta.sma(src, len)
        "EMA" => ta.ema(src, len)
        "WMA" => ta.wma(src, len)
        => ta.rma(src, len)
 
// ATR function
getATR(len) =>
    ta.atr(len)
 
// Stop function
calcStop(entry, atrVal, mult, isLong) =>
    isLong ? entry - atrVal * mult : entry + atrVal * mult
 
// Signal function
getSignal(ma1, ma2) =>
    long = ta.crossover(ma1, ma2)
    short = ta.crossunder(ma1, ma2)
    [long, short]
 
// === EXECUTE ===
maValue = ma(close, maLength, maType)
atrValue = getATR(atrLength)
 
// Long stop
longStop = calcStop(close, atrValue, atrMultiplier, true)
shortStop = calcStop(close, atrValue, atrMultiplier, false)
 
// Signals
[buySignal, sellSignal] = getSignal(close, maValue)
 
// === PLOT ===
plot(maValue, color=color.blue, title=maType)
plot(longStop, color=color.red, title="Long Stop")
plot(shortStop, color=color.green, title="Short Stop")
 
plotshape(buySignal, location=location.belowbar, style=shape.labelup, color=color.lime)
plotshape(sellSignal, location=location.abovebar, style=shape.labeldown, color=color.red)

Best Practices

  1. Descriptive names - calculateRSI not calc
  2. Single responsibility - Each function one task
  3. Document complex functions - Add comments
  4. Test thoroughly - Verify outputs
  5. Keep simple - Don’t over-engineer

Next Steps

Functions are the building blocks of clean code.

Graph View

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