TRANSFORM

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Syntax

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Scalar

transform(array, lambda)

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Arguments

• T is the array element type: BOOLEAN, TINYINT, SMALLINT, INTEGER, BIGINT, FLOAT, DOUBLE, DECIMAL(p, s), STRING, BINARY, DATE, TIME, TIMESTAMP, ARRAY, MAP or STRUCT.
• U is the result type of the lambda or finish expression: BOOLEAN, TINYINT, SMALLINT, INTEGER, BIGINT, FLOAT, DOUBLE, DECIMAL(p, s), STRING, BINARY, DATE, TIME, TIMESTAMP, ARRAY, MAP or STRUCT.

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Returns

• Type: ARRAY<U>
• Possible values: The lambda results.
• NULL behavior: NULL array returns NULL; NULL elements are passed to the lambda. NULL lambda results become NULL elements.
• Shape: Same number of elements as input.
• Ordering: Input encounter order.

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Properties

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Usage notes

• The optional lambda index is zero-based.
• INTEGER and INT mean the same type; STRING means VARCHAR text. NULL can be used with a supported type. Cast NULL explicitly when its type would otherwise be unclear.

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Examples

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Typical behavior

SELECT transform(ARRAY[1, 2, 3], x -> x + 1) AS "value";

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Transform strings

SELECT transform(ARRAY('red', 'blue'), x -> upper(x)) AS colors;

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Limitations

• The same input gives repeatable results only when the supplied lambda does. Avoid random or other changing expressions when you need reproducible results.