LAMBDA function

You can create and return a custom function with a set of names and a formula_expression that uses them. To calculate the formula_expression, you can call the returned function with as many values as the name declares.

Sample Usage

LAMBDA(Salary, Salary*0.3)(1000)

LAMBDA(Temp, (5/9)*(Temp-32))(85)

Syntax

LAMBDA(name, formula_expression)

• name: The name to be used inside the formula_expression. This name must be an identifier and resolves to the actual value passed to the custom function returned by LAMBDA.
• formula_expression: The formula to be calculated. It uses names declared in previous parameters.

Notes

• If a named function expects another function as an input in an argument inside a named function, you can use a LAMBDA or a named function.

Examples

Example data:

LAMBDA standalone

You can write a LAMBDA function to calculate salary tax, assuming that the tax rate is 30%. You input the salary value after the function.

Example: =LAMBDA(salary, salary*0.3)(C5)

This calculates the tax for month 1.

LAMBDA inside a LAMBDA helper function

To perform advanced array-operations, use LAMBDA functions inside LAMBDA helper functions (LHFs).

Example: =MAP(C5:C10, LAMBDA(salary, salary*0.3))

This performs the calculation of salary * 0.3 to each item in the C5:C10 array.

LAMBDA inside a named function

You can use LAMBDA functions as a part of a named function’s argument. Learn more about named functions.

Named function: AVG_MONTHLY_TAX(range, tax_calculator_function)

Formula definition: =tax_calculator_function(sum(range))/count(range)

You can write the tax_calculator_function argument with a LAMBDA function.

Example: =AVG_MONTHLY_TAX(C5:C10,LAMBDA(range, range*0.3))

This calculates the average monthly tax for months 1–6.

Common errors

The name argument isn’t an identifier

Example: =LAMBDA(3, x+1)(3)

If the first argument isn't an identifier, this error occurs:

Identifier requirements:

• Can’t be ranges, like “A1” or “A2.”
• Can’t have spaces or special characters. Dots and underscores are allowed.
• Can’t start with numbers, like “9hello.”

The LAMBDA wasn’t called

This error is due to not following the LAMBDA with the call that contains the values.

Example: =LAMBDA(salary, salary*0.3)

If no value is passed for salary, this error occurs:

For a LAMBDA, as an argument in a named function, this means not calling the placeholder referring to that LAMBDA with the needed values inside the named function's definition.

Example: Under formula definition, if you write =tax_calculator_function/count(range)

instead of =tax_calculator_function(sum(range))/count(range), this error occurs:

Tip: For a LAMBDA inside a LAMBDA helper function, this error wouldn’t occur because the LAMBDA helper function automatically uses the LAMBDA on the given input range.

Lambda helper functions

Lambda helper functions (LHFs) are native functions which accept a reusable LAMBDA as an argument along with an input array(s). They help in advanced array-operations by executing the formula specified inside the LAMBDA, on each value in the input array. The reusable LAMBDA can be passed either as a LAMBDA function or a named function.
Lambda helper functions:

• MAP function: This function maps each value in the given arrays to a new value. 
• REDUCE function: This function reduces an array to an accumulated result. 
• BYCOL function: This function groups an array by columns.
• BYROW function: This function groups an array by rows.
• SCAN function: This function scans an array and produces intermediate values.
• MAKEARRAY function: This function creates a calculated array of specified dimensions.

Related functions

Create & use named functions: Let users create and store custom functions, similar to LAMBDA.