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For Loops in Pine Script

· 9 min read
Pineify Team
Pineify Team

Pine Script, TradingView's proprietary language, allows users to create custom trading tools and strategies. Among the essential programming concepts in Pine Script is the for loop, which facilitates the repetition of a block of code for a specified number of times. This article will cover the syntax, applications, and best practices for utilizing for loops in Pine Script to enhance your trading scripts.

For Loops in Pine Script

Syntax​

For loops are fundamental for performing repetitive tasks, such as calculations and data analysis, within a defined range.

The basic structure of a for loop in Pine Script is:

for counter = start_value to end_value
    // Code to be repeated
  • counter: A variable that increments with each iteration of the loop.
  • start_value: The initial value of the counter.
  • end_value: The maximum value the counter can reach, determining when the loop stops.

How For Loops Work​

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A for loop executes a block of code repeatedly, incrementing the counter variable after each iteration until it reaches the end value.

Practical Applications

For loops are useful for various tasks in Pine Script:

  • Analyzing historical data.
  • Managing arrays.
  • Implementing complex trading logic.
  • Performing iterative calculations.

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Examples of For Loops​

For loops can be used to perform calculations and create visualizations. However, plots can only work outside local scopes, so you can only see the final loops result using a plot. To overcome this limitation, use labels inside the local scope.

The below examples demonstrate how to use "for" loops in Pine Script for different applications.

Simple Moving Average (SMA)​

The math behind the SMA is you loop over the last N bars, add up the series value you want to average from each one, then divide by N.


// This source code is subject to the terms of the Mozilla Public License 2.0 at https://mozilla.org/MPL/2.0/
// © Pineify

//======================================================================//
//                    ____  _            _  __                          //
//                   |  _ \(_)_ __   ___(_)/ _|_   _                    //
//                   | |_) | | '_ \ / _ \ | |_| | | |                   //
//                   |  __/| | | | |  __/ |  _| |_| |                   //
//                   |_|   |_|_| |_|\___|_|_|  \__, |                   //
//                                             |___/                    //
//======================================================================//

//@version=6
indicator("[Pineify - Best Pine Script Generator] SMA with For Loop", overlay=true)

length = input.int(30, title="SMA Length")
src = close

sum = 0.0
for i = 0 to length - 1
    sum := sum + src[i]

sma = sum / length

plot(sma, color=color.blue, title="SMA")

In this example:

  • The script calculates the SMA of the closing prices over a specified length.
  • The for loop iterates through the last 'length' bars, summing their closing prices.
  • The SMA is then calculated by dividing the sum by the length.

Counting High and Low Bars​

This example counts the number of bars with a high greater or lower than the current bar’s high over a user-defined lookback period.

// This source code is subject to the terms of the Mozilla Public License 2.0 at https://mozilla.org/MPL/2.0/
// © Pineify

//======================================================================//
//                    ____  _            _  __                          //
//                   |  _ \(_)_ __   ___(_)/ _|_   _                    //
//                   | |_) | | '_ \ / _ \ | |_| | | |                   //
//                   |  __/| | | | |  __/ |  _| |_| |                   //
//                   |_|   |_|_| |_|\___|_|_|  \__, |                   //
//                                             |___/                    //
//======================================================================//

//@version=6
indicator("`[Pineify - Best Pine Script Generator] for` loop", overlay=true)
lookbackInput = input.int(50, "Lookback in bars", minval = 1, maxval = 4999)
higherBars = 0
lowerBars = 0
if barstate.islast
    var label lbl = label.new(na, na, "", style = label.style_label_left)
    for i = 1 to lookbackInput
        if high[i] > high
            higherBars += 1
        else if high[i] < high
            lowerBars += 1
    label.set_xy(lbl, bar_index, high)
    label.set_text(lbl, str.tostring(higherBars, "# higher bars\\n") + str.tostring(lowerBars, "# lower bars"))

In this example:

  • lookbackInput: Defines the number of bars to look back.
  • for i = 1 to lookbackInput: Loops from 1 to the user-defined lookback period.
  • Inside the loop, we compare the high of each past bar (high[i]) to the bar’s high (high). Depending on the comparison, we increment either higherBars or lowerBars.
  • Finally, a label is created to display the count of higher and lower bars.

Looping Through Arrays​

Arrays are very important for Pine Script. Use the “for/in” statement to iterate through an array.

// This source code is subject to the terms of the Mozilla Public License 2.0 at https://mozilla.org/MPL/2.0/
// © Pineify

//======================================================================//
//                    ____  _            _  __                          //
//                   |  _ \(_)_ __   ___(_)/ _|_   _                    //
//                   | |_) | | '_ \ / _ \ | |_| | | |                   //
//                   |  __/| | | | |  __/ |  _| |_| |                   //
//                   |_|   |_|_| |_|\___|_|_|  \__, |                   //
//                                             |___/                    //
//======================================================================//

//@version=6
indicator("[Pineify - Best Pine Script Generator] For-In"， overlay=true)

arr = array.from(1, 5, 2, 4 , 3)
if barstate.islast
    label.new(bar_index, close, str.tostring(arr))

sum = 0
for el in arr
    sum += el

if barstate.islast
    label.new(bar_index + 5, close, str.tostring(sum))

sum_even = 0
for [ind, el] in arr
    if ind % 2 == 1
        sum_even += el

if barstate.islast
    label.new(bar_index + 10, close, str.tostring(sum_even))

plot(close)

In this example:

  • The script defines an array arr with some initial values.
  • It calculates the sum of all elements in the array using a for/in loop.
  • It calculates the sum of elements with odd indices using a for/in loop.
  • The array and the calculated sums are displayed using labels on the chart.

Controlling Loop Execution​

Pine Script provides keywords to control the flow of for loops:

  • break: Exits the loop prematurely based on a condition.
  • continue: Skips the current iteration and proceeds to the next.

Here's an example illustrating the use of break and continue :

// This source code is subject to the terms of the Mozilla Public License 2.0 at https://mozilla.org/MPL/2.0/
// © Pineify

//======================================================================//
//                    ____  _            _  __                          //
//                   |  _ \(_)_ __   ___(_)/ _|_   _                    //
//                   | |_) | | '_ \ / _ \ | |_| | | |                   //
//                   |  __/| | | | |  __/ |  _| |_| |                   //
//                   |_|   |_|_| |_|\___|_|_|  \__, |                   //
//                                             |___/                    //
//======================================================================//

//@version=6
indicator(" [Pineify - Best Pine Script Generator] Loop Control", overlay=false)

length = 10
sum = 0

for i = 1 to length
    if i == 3
        continue  // Skip iteration when i equals 3
    if i == 7
        break     // Exit loop when i equals 7
    sum := sum + i

plot(sum, title="Sum")

In this example:

  • The loop calculates the sum of numbers from 1 to 10, but skips the iteration when i is 3 and exits the loop when i is 7.

Best Practices

To write efficient and effective for loops in Pine Script, consider the following:

  • Always define the loop's start and end values clearly.
  • Avoid infinite loops by ensuring the loop condition will eventually be met.
  • Use break and continue statements judiciously to optimize loop execution.
  • Be mindful of the scope of variables used within the loop.
  • Ensure that plots only work outside local scopes.

Conclusion​

For loops are a powerful tool for automating repetitive tasks and implementing complex logic in Pine Script. Understanding how to use for loops effectively can significantly enhance your ability to create custom trading indicators and strategies on TradingView. By mastering this concept and following best practices, you can unlock new possibilities in your trading scripts and improve your technical analysis.

Next Steps

Ready to take your Pine Script skills to the next level? Explore these resources:

  • Best Pine Script Generator.
  • TradingView's Pine Script documentation.
  • Online tutorials and courses.
  • Pine Script communities and forums.

Start experimenting with for loops in your own scripts and discover the endless possibilities for creating custom trading tools.