transform function
Applies to: 
Databricks SQL Databricks Runtime
Transforms elements in an array in expr using the function func.
Syntax
transform(expr, func)
Arguments
expr: An ARRAY expression.func: A lambda function.
Returns
An ARRAY of the type of the lambda function’s result.
The lambda function must have 1 or 2 parameters. The first parameter represents the element, the optional second parameter represents the index of the element.
The lambda function produces a new value for each element in the array.
Examples
> SELECT transform(array(1, 2, 3), x -> x + 1);
[2,3,4]
> SELECT transform(array(1, 2, 3), (x, i) -> x + i);
[1,3,5]