get_item

Description

Given an array, and a computed index, return the item at that index in the array. The first item has index 0. As opposed to array_slice(), this index may not be negative – you have to calculate the array_length() and subtract from it yourself, if you want an index from the end, or you can re-formulate the operation using array_slice(), at some performance penalty.

If there is no such item, this function returns null().

If you know the exact index you want, e g, the value does not need to be computed, then it is more efficient to index using regular brackets: myarray[3] is more efficient than get_item(myarray, 3).

Return type

any

Domain

This is a scalar function (calculates a single output value for a single input row.)

Categories

• Semistructured

Usage

get_item( array, item )

Argument	Type	Required	Multiple
array	array	Required	Only one
item	int64	Required	Only one

Examples

make_col someindex:1
make_col somearray:array(parse_json("[5,17,3,8,2,20]"))
make_col final:int64(get_item(somearray, someindex))
drop_col someindex, somearray

Make a new column final that contains the value 17. It does this by constructing an array in a temporary column somearray and an index in a temporary column someindex and then looking up the value of that index in the array. Because object lookup returns variant, the code casts the value to an int64.