Struct arrow::array::UnionArray

pub struct UnionArray { /* fields omitted */ }

An Array that can represent slots of varying types.

Each slot in a UnionArray can have a value chosen from a number of types. Each of the possible types are named like the fields of a StructArray. A UnionArray can have two possible memory layouts, “dense” or “sparse”. For more information on please see the specification.

[UnionBuilder]can be used to create UnionArray’s of primitive types. UnionArray’s of nested types are also supported but not via UnionBuilder, see the tests for examples.

Implementations

impl UnionArray

pub fn new(
    type_ids: Buffer,
    value_offsets: Option<Buffer>,
    child_arrays: Vec<(Field, ArrayRef)>,
    bitmap_data: Option<Buffer>
) -> Self

Creates a new UnionArray.

Accepts type ids, child arrays and optionally offsets (for dense unions) to create a new UnionArray. This method makes no attempt to validate the data provided by the caller and assumes that each of the components are correct and consistent with each other. See try_new for an alternative that validates the data provided.

Data Consistency

The type_ids Buffer should contain i8 values. These values should be greater than zero and must be less than the number of children provided in child_arrays. These values are used to index into the child_arrays.

The value_offsets Buffer is only provided in the case of a dense union, sparse unions should use None. If provided the value_offsets Buffer should contain i32 values. These values should be greater than zero and must be less than the length of the overall array.

In both cases above we use signed integer types to maintain compatibility with other Arrow implementations.

In both of the cases above we are accepting Buffer’s which are assumed to be representing i8 and i32 values respectively. Buffer objects are untyped and no attempt is made to ensure that the data provided is valid.

pub fn try_new(
    type_ids: Buffer,
    value_offsets: Option<Buffer>,
    child_arrays: Vec<(Field, ArrayRef)>,
    bitmap: Option<Buffer>
) -> Result<Self>

Attempts to create a new UnionArray and validates the inputs provided.

pub fn child(&self, type_id: i8) -> ArrayRef

Accesses the child array for type_id.

Panics

Panics if the type_id provided is less than zero or greater than the number of types in the Union.

pub fn type_id(&self, index: usize) -> i8

Returns the type_id for the array slot at index.

Panics

Panics if index is greater than the length of the array.

pub fn value_offset(&self, index: usize) -> i32

Returns the offset into the underlying values array for the array slot at index.

Panics

Panics if index is greater than the length of the array.

pub fn value(&self, index: usize) -> ArrayRef

Returns the array’s value at index.

Panics

Panics if index is greater than the length of the array.

pub fn type_names(&self) -> Vec<&str>

Returns the names of the types in the union.

Trait Implementations

impl Array for UnionArray

fn as_any(&self) -> &dyn Any

Returns the array as Any so that it can be downcasted to a specific implementation.

fn data(&self) -> &ArrayData

Returns a reference to the underlying data of this array.

fn data_ref(&self) -> &ArrayData

Returns a reference-counted pointer to the underlying data of this array.

fn data_type(&self) -> &DataType

Returns a reference to the DataType of this array.

fn slice(&self, offset: usize, length: usize) -> ArrayRef

Returns a zero-copy slice of this array with the indicated offset and length.

fn len(&self) -> usize

Returns the length (i.e., number of elements) of this array.

fn is_empty(&self) -> bool

Returns whether this array is empty.

fn offset(&self) -> usize

Returns the offset into the underlying data used by this array(-slice). Note that the underlying data can be shared by many arrays. This defaults to 0.

fn is_null(&self, index: usize) -> bool

Returns whether the element at index is null. When using this function on a slice, the index is relative to the slice.

fn is_valid(&self, index: usize) -> bool

Returns whether the element at index is not null. When using this function on a slice, the index is relative to the slice.

fn null_count(&self) -> usize

Returns the total number of null values in this array.

fn get_buffer_memory_size(&self) -> usize

Returns the total number of bytes of memory pointed to by this array. The buffers store bytes in the Arrow memory format, and include the data as well as the validity map.

fn get_array_memory_size(&self) -> usize

Returns the total number of bytes of memory occupied physically by this array. This value will always be greater than returned by get_buffer_memory_size() and includes the overhead of the data structures that contain the pointers to the various buffers.

fn to_raw(&self) -> Result<(*const FFI_ArrowArray, *const FFI_ArrowSchema)>

returns two pointers that represent this array in the C Data Interface (FFI)

impl Debug for UnionArray

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl From<ArrayData> for UnionArray

fn from(data: ArrayData) -> Self

Performs the conversion.

impl JsonEqual for UnionArray

fn equals_json(&self, _json: &[&Value]) -> bool

Checks whether arrow array equals to json array.

fn equals_json_values(&self, json: &[Value]) -> bool

Checks whether arrow array equals to json array.