This function scans an array and produces intermediate values by application of a LAMBDA
function to each value. Returns an array of the intermediate values obtained at each step.
Sample Usage
SCAN(5, A1:A3, LAMBDA(accumulator, current_value, accumulator+current_value))
SCAN(2, A1:A3, LAMBDA(accumulator, current_value, accumulator*current_value))
Syntax
SCAN(initial_value, array_or_range, LAMBDA)
initial_value
: The initialaccumulator
value.array_or_range
: An array or range to be scanned.LAMBDA
: ALAMBDA
that’s applied to each value inarray_or_range
for scanning it. Syntax:
LAMBDA(name1, name2, formula_expression)
 Requirements:
 The
LAMBDA
must have exactly 2name
arguments along with aformula_expression
which uses thosenames
. Thename1
resolves to the current value in theaccumulator
andname2
resolves to thecurrent_value
inarray_or_range
, when applying theLAMBDA
. Theaccumulator
is updated in each step to the intermediate value obtained in the previous step.
 The
 Syntax:
Notes
 The passed
LAMBDA
should accept exactly 2name
arguments, otherwise an#N/A
error is returned. These arguments correspond toaccumulator
andcurrent_value
, in order. These are explained as:name1
: Resolves to the valueaccumulator
.name2
: Resolves to thecurrent_value
in the input array.
 The
accumulator
is initialized byinitial_value
and updated in each step to the intermediate value obtained in the previous step.

The
current_value
in the input array are found row by row, while you apply theLAMBDA.
 A
named function
can be passed for theLAMBDA
parameter and behaves like aLAMBDA
in this case. Learn more about named functions. The
named function
must follow theLAMBDA
syntax forSCAN
with exactly 2 argument placeholders defined for it.  The
named function
shouldn't be followed by parenthesis.
 The
Examples
Return the running total of an array
Example data:
A 


1 
4 
2 
2 
3 
1 
Example: =SCAN(5, A1:A3, LAMBDA(accumulator, current_value, accumulator+current_value))
Result:
9 
11 
12 
Return the cumulative percentage of total value
Example data:
A 


1 
4 
2 
2 
3 
1 
Example: =SCAN(0, A1:A3, LAMBDA(accumulator, current_value, accumulator + current_value/sum(A1:A3)))
Result:
0.57 
0.85 
1 
Return the running total of an array and restart calculation when the number is 0 with a named function as LAMBDA.
Example data:
A 


1 
4 
2 
2 
3 
1 
4 
0 
5 
3 
6 
6 
Example: =SCAN(0, A1:A6, RUNNING_TOTAL_0)
Named function: RUNNING_TOTAL_0
is a named function
which outputs the running total of the array and restarts the calculation when the current_value
is 0.
Formula definition: =if(current_value=0, current_value, accumulator+current_value)
, where accumulator
and current_value
are argument placeholders defined for RUNNING_TOTAL_0
.
Result:
4 
6 
7 
0 
3 
9 
Common Errors
The passed LAMBDA doesn't have exactly 2 name argumentsIf the LAMBDA
function doesn’t have 2 name
arguments, this error occurs:
“Wrong number of arguments to LAMBDA. Expected 3 arguments, but got 2 arguments."
Example: =SCAN(5, C1:C4, LAMBDA(current_value, current_value+1))
In this example, LAMBDA was given only 1 name
argument when it needed 2.
If the last parameter of SCAN
function wasn’t a LAMBDA
function, this error occurs:
“Argument must be a LAMBDA.”
Example: =SCAN(5, C1:C4, 3)
In this example the last function is 3
, instead of a LAMBDA
function.
If 1 or more name
arguments aren’t valid, this error occurs:
“Argument 1 of function LAMBDA is not a valid name.”
Example: =SCAN(5, C1:C4, LAMBDA(C1, v, C1+v))
In this example, C1
is an invalid name
since it clashes with a range.
If the application of LAMBDA
on the input array produces any nonsingle intermediate value, this error occurs:
“Single value expected. Nested array results are not supported.”
Example: =SCAN(5, C1:C4, LAMBDA(accumulator, value, {accumulator, value}))
Every application of LAMBDA
must produce an intermediate value which is a single value only and can’t be another array.
Related functions
 LAMBDA function: This function lets you create and return a custom function with a set of
names
and aformula_expression
that uses them.  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.
 BYROW function: This function groups an array by rows.
 BYCOL function: This function groups an array by columns.
 MAKEARRAY function: This function creates a calculated array of specified dimensions.
 Create & use named functions: This function lets users create and store custom functions, similar to
LAMBDA
.