List Functions

Example Graph

The following examples run against this graph:

append()

Adds an element to the end of a list and returns the new list.

LET myList = ["a", 1, 2]
RETURN append(myList, "b")

Result:

difference()

Returns the difference between two lists, producing a new list of elements found in the first input list but not in the second. Duplicates are included.

LET l1 = [1,2,2,3], l2 = [3,4,5]
RETURN difference(l1, l2)

Result:

elements()

Returns a list containing the nodes and edges that make up a path.

MATCH p = ()->()
LET items = elements(p)
FOR item IN items WITH ORDINALITY index
FILTER index %2 = 1
RETURN item

Result: item

head()

Returns the first element in a list.

LET myList = ["a", 1, 2]
RETURN head(myList)

Result:

intersection()

Returns the intersection of two lists, producing a new list of elements common to both. Duplicates are included.

LET l1 = [1,2,3,3], l2 = [3,3,4,5]
RETURN intersection(l1, l2)

Result:

listContains()

Checks whether a specified element exists in a list, returning 1 for true and 0 for false.

LET myList = ["a", 1, 2]
RETURN listContains(myList, "b")

Result:

listUnion()

Returns the union of two lists, producing a new list of elements from either input list. Duplicates are removed.

LET l1 = [1,2,2,3], l2 = [3,4,5]
RETURN listUnion(l1, l2)

Result:

reduce()

Performs a calculation iteratively using each element in a list. With a specified intital value, the defined calculation takes the first element in the list as input.

LET myList = [1,3,5]
RETURN reduce(_sum = 0, item in myList | _sum + item) AS listSum

Result:

MATCH p = ({_id: "P1"})-[edges]->{2}()
RETURN reduce(total = 0, edge in edges | total + edge.weight) as totalWeights

Result:

size()

Returns the number of elements in a list.

LET myList = [1, 2, null, 3]
RETURN size(myList)

Result:

trim()

Removes a specified number of elements from the right end of the list.

LET myList = [1, 2, null, 3]
RETURN trim(myList, 2)

Result: