# Functions

This section contains the list of supported functions.

Name | Description |
---|---|

`startNode` | Returns the starting node of an edge. |

`endNode` | Returns the destination node of an edge. |

`degree` | Returns the number of edges (both incoming and outgoing) of a node. |

`head` | Returns the first element of a list. |

`last` | Returns the last element of a list. |

`properties` | Returns the properties of a node or an edge. |

`size` | Returns the number of elements in a list or a map. When given a string it returns the number of characters. When given a path it returns the number of expansions (edges) in that path. |

`toBoolean` | Converts the argument to a boolean. |

`toFloat` | Converts the argument to a floating point number. |

`toInteger` | Converts the argument to an integer. |

`type` | Returns the type of an edge as a character string. |

`keys` | Returns a list keys of properties from an edge or a node. Each key is represented as a string of characters. |

`labels` | Returns a list of labels from a node. Each label is represented as a character string. |

`nodes` | Returns a list of nodes from a path. |

`relationships` | Returns a list of relationships (edges) from a path. |

`range` | Constructs a list of value in given range. |

`tail` | Returns all elements after the first of a given list. |

`uniformSample` | Returns elements of given list randomly oversampled or undersampled to desired size, e.g. `uniformSample([1, 2, 3], 5) -> [1, 2, 3, 2, 3]` |

`abs` | Returns the absolute value of a number. |

`ceil` | Returns the smallest integer greater than or equal to given number. |

`floor` | Returns the largest integer smaller than or equal to given number. |

`round` | 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. |

`exp` | Calculates `e^n` where `e` is the base of the natural logarithm, and `n` is the given number. |

`log` | Calculates the natural logarithm of a given number. |

`log10` | Calculates the logarithm (base 10) of a given number. |

`sqrt` | Calculates the square root of a given number. |

`acos` | Calculates the arccosine of a given number. |

`asin` | Calculates the arcsine of a given number. |

`atan` | Calculates the arctangent of a given number. |

`atan2` | Calculates the arctangent2 of a given number. |

`cos` | Calculates the cosine of a given number. |

`sin` | Calculates the sine of a given number. |

`tan` | Calculates the tangent of a given number. |

`sign` | 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. |

`e` | Returns the base of the natural logarithm. |

`pi` | Returns the constant pi. |

`rand` | Returns a random floating point number between 0 (inclusive) and 1 (exclusive). |

`startsWith` | Check if the first argument starts with the second. |

`endsWith` | Check if the first argument ends with the second. |

`contains` | Check if the first argument has an element which is equal to the second argument. |

`left` | Returns a string containing the specified number of leftmost characters of the original string. |

`lTrim` | Returns the original string with leading whitespace removed. |

`replace` | Returns a string in which all occurrences of a specified string in the original string have been replaced by another (specified) string. |

`reverse` | Returns a string in which the order of all characters in the original string have been reversed. |

`right` | Returns a string containing the specified number of rightmost characters of the original string. |

`rTrim` | Returns the original string with trailing whitespace removed. |

`split` | Returns a list of strings resulting from the splitting of the original string around matches of the given delimiter. |

`substring` | Returns a substring of the original string, beginning with a 0-based index start and length. |

`toLower` | Returns the original string in lowercase. |

`toString` | Converts an integer, float or boolean value to a string. |

`toUpper` | Returns the original string in uppercase. |

`trim` | Returns the original string with leading and trailing whitespace removed. |

`all` | Check if all elements of a list satisfy a predicate. The syntax is: `all(variable IN list WHERE predicate)` .NOTE: Whenever possible, use Memgraph's lambda functions when matching instead. |

`single` | Check if only one element of a list satisfies a predicate. The syntax is: `single(variable IN list WHERE predicate)` . |

`reduce` | Accumulate list elements into a single result by applying an expression. The syntax is: `reduce(accumulator = initial_value, variable IN list \| expression)` . |

`extract` | A list of values obtained by evaluating an expression for each element in list. The syntax is: `extract(variable IN list \| expression)` . |

`assert` | Raises an exception reported to the client if the given argument is not `true` . |

`counter` | Generates integers that are guaranteed to be unique within a single query for a given counter name. The syntax is `counter("counter_name", initial_value, [increment] = 1)` . The increment parameter can be any integer besides zero. |

`timestamp` | Returns the difference, measured in milliseconds, between the current time and midnight, January 1, 1970 UTC. |

`id` | Returns identifier for a given node or edge. The identifier is generated during the initialization of node or edge and will be persisted through the durability mechanism. |