MAP

Apply the same calculation to every item in a list.

Use MAP when you have a list of items (prices, names, numbers) and need to transform each one the same way. Common scenarios: adding tax to all prices, formatting customer names consistently, calculating discounts for a product catalog.

How it works

MAP(array, function(argument: transformation))

• array - The list of items you want to transform

• function(argument: transformation) - A function that defines what to do with each item

The function syntax works like this: you define an argument name, then use it in your transformation formula.

Examples

Add tax to all prices

You have a list of product prices and need to add 21% VAT to each one.

MAP(PRODUCT_PRICES, function(PRICE: PRICE * 1.21))

Takes your list of prices and returns a new list with 21% VAT added to each.

Format customer names

Convert all customer names to proper Title Case.

MAP(CUSTOMER_NAMES, function(NAME: TOCAPITALCASE(NAME)))

Transforms "john doe" into "John Doe" for every name in the list.

Volume discount per item

Apply 10% discount to any quantity over 100.

MAP(ORDER_QUANTITIES, function(QTY: IF(QTY > 100, QTY * 0.90, QTY)))

Checks each quantity and applies the discount only where applicable.

Extract specific data from objects

Pull out just the email addresses from a list of customer objects.

MAP(CUSTOMERS, function(CUSTOMER: CUSTOMER.email))

Returns a simple list of email addresses from complex customer data.

Combining MAP with other functions

Calculate total with tax

SUM(MAP(PRICES, function(PRICE: PRICE * 1.21)))

Adds tax to all prices, then sums them for a total.

Count items meeting a condition

SUM(MAP(QUANTITIES, function(QTY: IF(QTY > 100, 1, 0))))

Counts how many items have quantities over 100.

Transform and filter

FILTER(
   MAP(PRODUCTS, function(P: P.price * 1.21)),
   function(PRICE: PRICE > 50)
)

Adds tax to all products, then filters to only show items over €50.

Common mistakes

• Missing function wrapper - MAP(LIST, PRICE * 1.21) won't work. You need MAP(LIST, function(PRICE: PRICE * 1.21))

• Thinking MAP changes the original - MAP creates a new list and leaves your original unchanged

• Using MAP to filter - If you want to remove items, use FILTER. MAP transforms items but keeps all of them

• Complex nested logic - If your function gets too complex, create intermediate variables first

When to use alternatives

• Filtering items out: Use FILTER instead

• Reducing to single value: Use REDUCE or aggregation functions like SUM, MEAN

• Simple operations on all items: Sometimes a direct formula works better than MAP

Related functions

FILTER, REDUCE, SOME, ALL