ARRAY_FIRST

Description

Use a lambda bool expression and an array as the input parameters, the lambda expression is used to evaluate the internal data of other input ARRAY parameters. Returns the first element in the array for which lambda(arr1[i]) returns something other than 0.

Syntax

ARRAY_FIRST(<lambda>, <arr>)

Parameters

Parameter	Description
<lambda>	A lambda expression where the input parameters must match the number of columns in the given array. The expression can execute valid scalar functions but does not support aggregate functions.
<arr>	ARRAY array

Return Value

Returns the index of the first non-zero value. If no such index is found, returns NULL.

Example

select array_first(x->x>2, [1,2,3,0]);

+------------------------------------------------------------------------------------------------+
| array_first(array_filter(ARRAY(1, 2, 3, 0), array_map([x] -> x(0) > 2, ARRAY(1, 2, 3, 0))), -1)|
+------------------------------------------------------------------------------------------------+
|                                                                                              3 |
+------------------------------------------------------------------------------------------------+

select array_first(x->x>4, [1,2,3,0]); 

+------------------------------------------------------------------------------------------------+
| array_first(array_filter(ARRAY(1, 2, 3, 0), array_map([x] -> x(0) > 4, ARRAY(1, 2, 3, 0))), -1)|
+------------------------------------------------------------------------------------------------+
|                                                                                           NULL |
+------------------------------------------------------------------------------------------------+

select array_first(x->x>1, [1,2,3,0]);

+---------------------------------------------------------------------------------------------+
| array_first(array_filter(ARRAY(1, 2, 3, 0), array_map([x] -> x > 1, ARRAY(1, 2, 3, 0))), 1) |
+---------------------------------------------------------------------------------------------+
|                                                                                           2 |
+---------------------------------------------------------------------------------------------+