Reduce array elements

Supported in: Batch, Streaming

Reduces array elements using an expression.

Expression categories: Array

Declared arguments

• Array: Array to reduce.
  Expression<Array<Array<Boolean | Byte | Date | Double | Float | Integer | Long | Map<AnyType, AnyType> | Short | String | Timestamp> | Boolean | Byte | Date | Double | Float | Integer | Long | Map<AnyType, AnyType> | Short | String | Timestamp>>
• Expression to reduce: The expression to apply once per element of the array.
  Expression<T>
• Initial value: This is the start value used to initialize the accumulator, if the array has a length of 0, this value will be returned.
  Expression<T>

Type variable bounds: T accepts Array<Boolean | Byte | Date | Double | Float | Integer | Long | Map<AnyType, AnyType> | Short | String | Timestamp> | Boolean | Byte | Date | Double | Float | Integer | Long | Map<AnyType, AnyType> | Short | String | Timestamp

Output type: T

Examples

Example 1: Base case

Argument values:

• Array: miles
• Expression to reduce:
  add(
   expressions: [accumulator, element],
  )
• Initial value: 0

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Example 2: Base case

Description: Return the first non null within the array. Argument values:

• Array: miles
• Expression to reduce:
  firstNonNull(
   expressions: [accumulator, element],
  )
• Initial value: init

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Example 3: Base case

Argument values:

• Array: miles
• Expression to reduce:
  concatStrings(
   expressions: [accumulator,
  cast(
   expression: element,
   type: String,
  )],
   separator: -,
  )
• Initial value: empty string

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Example 4: Null case

Description: Null arrays will return null outputs. Argument values:

• Array: miles
• Expression to reduce:
  firstNonNull(
   expressions: [accumulator, element],
  )
• Initial value: init

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Example 5: Edge case

Description: Empty array will return the initial value. Argument values:

• Array: miles
• Expression to reduce:
  add(
   expressions: [accumulator, element],
  )
• Initial value: 0

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