How to get the largest value from a Pine Script array?

How to get the largest value from a Pine Script array?

TL;DR
Populate a float array and call array.max(myArray) to retrieve its highest stored value, then update your logic whenever that maximum changes.

At a Glance

Difficulty	Beginner
Time to implement	5-10 min
Category	Arrays

Quick Actions

• Open in AI Editor
• Browse PineScript Examples
• Connect to Live Trading

Quick Start

//@version=5
indicator("Array max demo", overlay=false)

var float[] swings = array.new_float()
if barstate.isnew
    array.unshift(swings, high)
    if array.size(swings) > 10
        array.pop(swings)

maxSwing = array.max(swings)
plot(maxSwing, "Highest stored high")

Tip. Initialise arrays with `var` so the collected values persist between bars; otherwise you rebuild the array from scratch every update.

Why It Matters

Arrays let you capture custom sets of data—swing highs, indicator outputs, custom metrics—and array.max() turns that storage into actionable thresholds. Whether you want to monitor the strongest reading in a rolling window or trigger alerts when a new peak prints, the maximum is a critical reference point.

What You’ll Learn

• Create and maintain arrays that hold the data you care about.
• Query the maximum value with array.max() and guard against empty arrays.
• Compare incoming values against the maximum to detect new extremes.
• Visualise or publish the maximum so traders see it at a glance.

Quick Reference

Call	Purpose
array.new_float(size)	Creates a float array to store numeric values.
array.unshift(id, value)	Pushes a value to the front of the array.
array.pop(id)	Removes the oldest element to keep the array bounded.
array.size(id)	Reports how many elements the array currently holds.
array.max(id)	Returns the largest element of the array.

Implementation Blueprint

1. Persist the array across bars
   Declare with var so the array survives every script execution.

   var float[] samples = array.new_float()

2. Insert and prune values
   Decide how many elements you need and keep the array bounded to that size.

   array.unshift(samples, close)
   if array.size(samples) > 50
       array.pop(samples)

3. Read and act on the maximum
   Guard against empty arrays, then fetch the max and compare it with the latest reading.

   float maxValue = na
   if array.size(samples) > 0
       maxValue := array.max(samples)
       isNewHigh = close >= maxValue

Example Playbook

//@version=5
indicator("Rolling range tracker", overlay=false, max_labels_count=500)

window        = input.int(20, "Window size", minval=1)
alertOnRecord = input.bool(true, "Alert on new max")

var float[] returns = array.new_float()

// Collect percentage returns and keep the window bounded
ret = math.abs(close / close[1] - 1.0)
if barstate.isnew
    array.unshift(returns, ret)
    if array.size(returns) > window
        array.pop(returns)

float rollingMax = na
if array.size(returns) > 0
    rollingMax := array.max(returns)

plot(rollingMax, "Largest % move", color=color.new(color.orange, 0))
plot(ret, "Current % move", color=color.new(color.blue, 0))

if alertOnRecord and not na(rollingMax) and ret >= rollingMax
    alert("New record intrabar move: " + str.tostring(ret * 100, format.percent))

if not na(rollingMax)
    label.new(bar_index, rollingMax,
        "Max: " + str.tostring(rollingMax * 100, format.percent),
        style=label.style_label_left,
        textcolor=color.white,
        bgcolor=color.new(color.orange, 70))

Why this works.

• The array holds a rolling window of returns, so the maximum always reflects recent volatility.
• Plotting both the current value and the maximum makes new records obvious.
• Alerts trigger the first time a bar matches or exceeds the stored maximum.

Pro Tips & Pitfalls

• Check array.size() before calling array.max() to avoid runtime errors on empty arrays.
• Use array.set(id, index, value) if you need to update elements in place before recomputing the maximum.
• array.max() runs in linear time; keep the array size reasonable if you call it every bar.
• For both min and max tracking, compute array.min() alongside the maximum and build a custom range indicator.

Troubleshooting & FAQ

array.max() throws a runtime error

It happens when the array is empty. Ensure you insert at least one element before reading the maximum, or guard with if array.size(arr) > 0.

The maximum never updates

Remember that inserting values at the end with array.push() leaves older values in place. If you keep the array bounded, make sure you remove the oldest items so the maximum can change.

Can I know which index holds the maximum?

Not directly. Store both the value and its index yourself (for example by scanning with a for loop and tracking the position whenever you see a new high).

Key Takeaways

• Persist arrays with var so they accumulate data between bars.
• Guard array.max() with a size check to avoid empty-array errors.
• Use the maximum to detect new extremes, adjust stops, or flag regime shifts.
• Combine array.max() with plotting and alerts for instant visibility when new records hit.

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Keep Going

• Open AI Editor to apply the pattern with guided assistance
• Browse Strategy Examples for ready-to-run templates
• Connect to Live Trading when you are ready to automate

Adapted from tradingcode.net, optimised for Algo Trade Analytics users.