SLICE function to return a new array from an existing array - MaxCompute

Returns a subset of an array, starting at a given index for a specified number of elements.

Syntax

HELPCODEESCAPE-plaintext
array<T> slice(array<T> <a>, <start>, <length>)

Parameters

Parameter	Required	Description
`a`	Yes	The input array. `T` can be any data type.
`start`	Yes	The index at which to start the slice. The minimum positive value is `1`. Negative values count from the end of the array, but elements are always returned left to right.
`length`	Yes	The number of elements to return. Must be `0` or greater. If `length` exceeds the number of elements remaining after `start`, the function returns all elements from `start` to the end of the array.

Usage notes

Indexing is 1-based: start = 1 refers to the first element.
A negative start counts from the end of the array. For example, start = -2 refers to the second-to-last element. Elements are still returned left to right.
Setting length = 0 returns an empty array.
If length exceeds the number of elements remaining after start, the function returns all remaining elements rather than raising an error.

Return value

Returns an ARRAY of the same element type T as the input array.

Examples

All examples use the array array(10, 20, 20, null, null, 30).

HELPCODEESCAPE-plaintext
-- Start at index 1, return 3 elements.
SELECT slice(array(10, 20, 20, null, null, 30), 1, 3);
-- [10, 20, 20]

-- Start at index -2 (second-to-last element), return 2 elements.
SELECT slice(array(10, 20, 20, null, null, 30), -2, 2);
-- [null, 30]

-- Start at index 3, request 10 elements (only 4 remain): returns all remaining.
SELECT slice(array(10, 20, 20, null, null, 30), 3, 10);
-- [20, null, null, 30]

-- Start at index 3, return 0 elements.
SELECT slice(array(10, 20, 20, null, null, 30), 3, 0);
-- []

Related functions

SLICE is a complex type function. For more information about functions for processing ARRAY, MAP, STRUCT, and JSON data, see Complex type functions.