functions.mdx

title	Functions
description	Unlock the graph analysis potential of Memgraph's wide-ranging built-in functions. Get started with tutorials and comprehensive documentation on Memgraph's collection of functions.

import { Callout } from 'nextra/components'

Functions

You can list all available functions in your current Memgraph instance with the following Cypher query:

CALL mg.functions() YIELD *;

User-defined functions

Memgraph offers the flexibility of implementing custom functions. When supported built-in functions are not enough, there is an option to define a custom one by using C, C++, Python or Rust. The mechanism of query modules enables the integration of custom functionalities.

Semantically, functions should be a small fragment of functionality that does not require long computations and large memory consumption. The only requirement for functions is not to modify the graph. Mentioned functionality offers flexibility in terms of nested calls within the Cypher.

Built-in functions

This section contains the list of supported functions.

Temporal functions

Name	Signature	Description
duration	duration(value: string|Duration) -> (Duration)	Returns the data type that represents a period of time.
date	date(value: string|Date|LocalDateTime|ZonedDateTime) -> (Date)	Returns the data type that represents a date with year, month, and day.
localTime	localTime(value: string|LocalTime|LocalDateTime|ZonedDateTime) -> (LocalTime)	Returns the data type that represents time within a day without timezone.
localDateTime	localDateTime(value: string|LocalDateTime|ZonedDateTime)-> (LocalDateTime)	Returns the data type that represents a date and local time.
datetime	datetime(value: NULL|string|map|ZonedDateTime)-> (ZonedDateTime)	Returns the ZonedDateTime value defined by the given parameters.

Scalar functions

Name	Signature	Description
assert	assert(expression: boolean, message: string = null) -> ()	Raises an exception if the given argument is not true.
coalesce	coalesce(expression: any [, expression: any]*) -> (any)	Returns the first non-null value in the given list of expressions.
counter	counter(name: string, initial-value: integer, increment: integer = 1) -> (integer)	Generates integers that are guaranteed to be unique within a single query for a given counter name. The increment parameter can be any integer besides zero.
degree	degree(node: Node) -> (integer)	Returns the number of relationships (both incoming and outgoing) of a node.
outDegree	outDegree(node: Node) -> (integer)	Returns the number of outgoing relationships of a node.
inDegree	inDegree(node: Node) -> (integer)	Returns the number of incoming relationships of a node.
endNode	endNode(relationship: Relationship) -> (Node)	Returns the destination node of a relationship.
head	head(list: List[any]) -> (any)	Returns the first element of a list.
id	id(value: Node|Relationship) -> (integer)	Returns identifier for a given node or relationship. The identifier is generated during the initialization of a node or a relationship and will be persisted through the durability mechanism.
last	last(list: List[any]) -> (any)	Returns the last element of a list.
properties	properties(value: Node|Relationship) -> (Map[string, any])	Returns the property map of a node or a relationship.
propertySize	propertySize(entity: Node|Relationship, property-name: string) -> (integer)	Returns the total amount of bytes stored in RAM for the property of a given entity node or relationship. For more information, check storage of properties inside Memgraph.
randomUUID	randomUUID() -> (string)	Returns randomly-generated Universally Unique Identifier (UUID)
size	size(value: List[any]|string|Map[string, any]|Path) -> (integer)	Returns the number of elements in the value. When given a list it returns the size of the list. When given a string it returns the number of characters. When given a path it returns the number of expansions (relationships) in that path.
startNode	startNode(relationship: Relationship) -> (Node)	Returns the starting node of a relationship.
toBoolean	toBoolean(value: boolean|integer|string) -> (boolean)	Converts the input argument to a boolean value, regardless of case sensitivity. The values true and false are directly converted to true or false, respectively. Additionally, the strings "true" and "t" are mapped to true, while the strings "false" and "f" are mapped to false.
toFloat	toFloat(value: number|string) -> (float)	Converts the argument to a floating point number.
toInteger	toInteger(value: boolean|number|string) -> (integer)	Converts the argument to an integer.
toString	toString(value: any) -> (string)	Converts the argument to a string. The function will error on unstringifiable types.
toStringOrNull	toStringOrNull(value: any) -> (string)	Converts the argument to a string. Returns null on unstringifiable types.
type	type(relationship: Relationship) -> (string)	Returns the type of a relationships as a character string.
timestamp	timestamp() -> (integer)	Returns the difference, measured in microseconds, between the current time and midnight, January 1, 1970 UTC.
valueType	valueType(any) -> (string)	Returns the value type of the object provided in textual format.

Pattern functions

Name	Signature	Description
exists	exists(pattern: Pattern)	Checks if a pattern exists as part of the filtering clause. Symbols provided in the MATCH clause can also be used here. The function can be used only with the WHERE clause.

Lists

Name	Signature	Description
all	all(variable IN list WHERE predicate)	Check if all elements of a list satisfy a predicate. NOTE: Whenever possible, use Memgraph's lambda functions when matching instead.
any	any(element IN list WHERE predicate_using_element)	Check if any element in the list satisfies the predicate.
extract	extract(variable IN list|expression)	A list of values obtained by evaluating an expression for each element in list.
labels	labels(node: Node) -> (List[string])	Returns a list of labels from a node. Each label is represented as string.
nodes	nodes(path: Path) -> (List[Node])	Returns a list of nodes from a path.
none	none(variable IN list WHERE predicate)	Returns true if the predicate is not satisfied for any element in the given list.
range	range(start-number: integer, end-number: integer, increment: integer = 1) -> (List[integer])	Constructs a list of value in given range.
reduce	reduce(accumulator = initial_value, variable IN list|expression)	Accumulate list elements into a single result by applying an expression.
relationships	relationships(path: Path) -> (List[Relationship])	Returns a list of relationships (edges) from a path.
single	single(variable IN list WHERE predicate)	Check if only one element of a list satisfies a predicate.
tail	tail(list: List[any]) -> (List[any])	Returns all elements after the first of a given list.
uniformSample	uniformSample(list: List[any], size: integer) -> (List[any])	Returns elements of a given list randomly oversampled or undersampled to desired size

Maps

Name	Signature	Description
keys	keys(map[Any, Any]|Node|Relationship) -> (List[Any])	Returns all keys of the map. In the case of node or a relationship, returns property keys.
values	values(map[Any, Any]|Node|Relationship) -> (List[Any])	Returns all values of the map. In the case of node or a relationship, returns property values.

Enum

Name	Signature	Description
ToEnum	ToEnum(value: string) -> (enum)	Gets enum value matching string of form name::value.
ToEnum	ToEnum(name: string, value: string) -> (enum)	Gets enum value passing name and value as separate strings.

Spatial

Name	Signature	Description
point	point(parameters: map) -> (null|point)	Creates a point data type from the given map.
point.distance	point.distance(x: null|point, y: null|point) -> (null|float)	Returns the distance between two points.
point.withinbbox	point.withinbbox(point: null|point, lower_left_corner: null|point, upper_right_corner: null|point) -> (null|boolean)	Returns whether the given point is contained within the bounding box made from lower_left_corner and upper_right_corner.

Math functions

Name	Signature	Description
abs	abs(number: integer|float) -> (integer|float)	Returns the absolute value of a number.
acos	acos(number: integer|float) -> (float)	Calculates the arccosine of a number between -1 and 1 in radians.
asin	asin(number: integer|float) -> (float)	Calculates the arcsine of a number between -1 and 1 in radians.
atan	atan(number: integer|float) -> (float)	Calculates the arctangent of a given number in radians.
atan2	atan2(y: integer|float, x: integer|float) -> (float)	Calculates a unique arctangent value from a set of coordinates in radians.
ceil	ceil(number: float) -> (integer)	Returns the smallest integer greater than or equal to the given float number.
cos	cos(number: integer|float) -> (float)	Calculates the cosine of an angle specified in radians.
e	e() -> (float)	Returns the base of the natural logarithm (2.71828)..
exp	exp(number: integer|float) -> (float)	Calculates e^n where e is the base of the natural logarithm, and n is the given number.
floor	floor(number: float) -> (integer)	Returns the largest integer smaller than or equal to the given float number.
log	log(number: integer|float) -> (float)	Calculates the natural logarithm of a given number.
log10	log10(number: integer|float) -> (float)	Calculates the logarithm (base 10) of a given number.
pi	pi() -> (float)	Returns the constant pi (3.14159).
rand	rand() -> (float)	Returns a random floating point number between 0 (inclusive) and 1 (exclusive).
round	round(number: float) -> (integer)	Returns the number, rounded to the nearest integer. Tie-breaking is done using the commercial rounding, where -1.5 produces -2 and 1.5 produces 2.
sign	sign(number: integer| float) -> (integer)	Applies the signum function to a given number and returns the result. The signum of positive numbers is 1, of negative -1 and for 0 returns 0.
sin	sin(number: integer|float) -> (float)	Calculates the sine of an angle specified in radians.
sqrt	sqrt(number: integer|float) -> (float)	Calculates the square root of a given number.
tan	tan(number: integer|float) -> (float)	Calculates the tangent of an angle specified in radians.

Aggregation functions

Name	Signature	Description
avg	avg(row: int|float) -> (float)	Returns an average value of rows with numerical values generated with the MATCH or UNWIND clause.
collect	collect(values: any) -> (List[any])	Returns a single aggregated list containing returned values.
collect	collect(key: string, value: any) -> (Map[string, any])	Returns a single aggregated map containing key-value pairs.
count	count(values: any) -> (integer)	Counts the number of non-null values returned by the expression.
max	max(row: integer|float|temporal) -> (integer|float|temporal)	Returns the maximum value in a set of values. Supported temporal types: Date, LocalTime, LocalDateTime and ZonedDateTime.
min	min(row: integer|float|temporal) -> (integer|float|temporal)	Returns the minimum value in a set of values. Supported temporal types: Date, LocalTime, LocalDateTime and ZonedDateTime.
sum	sum(row: integer|float) -> (integer|float)	Returns a sum value of rows with numerical values generated with the MATCH or UNWIND clause.

All aggregation functions can be used with the `DISTINCT` operator to perform calculations only on unique values. For example, `count(DISTINCT n.prop)` and `collect(DISTINCT n.prop)`.

Graph projection functions

Name	Signature	Description
project	project(row: path) -> map("nodes":list[Node], "edges":list[Edge])	Creates a projected graph consisting of nodes and relationships from aggregated paths.
project	project(nodes: List[Node], edges:List[Edge]) -> map("nodes":list[Node], "edges":list[Edge])	Creates a projected graph consisting of nodes and relationships from a list of nodes and a list of relationships, ignoring duplicate nodes and relationships.

String functions

Name	Signature	Description
contains	contains(string: string, substring: string) -> (boolean)	Check if the first argument has an element which is equal to the second argument.
endsWith	endsWith(string: string, substring: string) -> (boolean)	Check if the first argument ends with the second.
left	left(string: string, count: integer) -> (string)	Returns a string containing the specified number of leftmost characters of the original string.
lTrim	lTrim(string: string) -> (string)	Returns the original string with leading whitespace removed.
replace	replace(string: string, search-string: string, replacement-string: string) -> (string)	Returns a string in which all occurrences of a specified string in the original string have been replaced by another (specified) string.
reverse	reverse(string: string) -> (string)	Returns a string in which the order of all characters in the original string have been reversed.
right	right(string: string, count: integer) -> (string)	Returns a string containing the specified number of rightmost characters of the original string.
rTrim	rTrim(string: string) -> (string)	Returns the original string with trailing whitespace removed.
split	split(string: string, delimiter: string) -> (List[string])	Returns a list of strings resulting from the splitting of the original string around matches of the given delimiter.
startsWith	startsWith(string: string, substring: string) -> (boolean)	Check if the first argument starts with the second.
substring	substring(string: string, start-index: integer, length: integer = null) -> (string)	Returns a substring of the original string, beginning with a 0-based index start and length.
toLower	toLower(string: string) -> (string)	Returns the original string in lowercase.
toUpper	toUpper(string: string) -> (string)	Returns the original string in uppercase.
trim	trim(string: string) -> (string)	Returns the original string with leading and trailing whitespace removed.

Conversion functions

Name	Signature	Description
convert.str2object	convert.str2object(string: string) -> (object: any)	Converts the input string to an object it presents.