Struct arrow_array::array::FixedSizeListArray

pub struct FixedSizeListArray { /* private fields */ }

An array of [fixed length lists], similar to JSON arrays (e.g. ["A", "B"]).

Lists are represented using a values child array where each list has a fixed size of value_length.

Use FixedSizeListBuilder to construct a FixedSizeListArray.

Representation

A FixedSizeListArray can represent a list of values of any other supported Arrow type. Each element of the FixedSizeListArray itself is a list which may contain NULL and non-null values, or may itself be NULL.

For example, this FixedSizeListArray stores lists of strings:

┌─────────────┐
│    [A,B]    │
├─────────────┤
│    NULL     │
├─────────────┤
│   [C,NULL]  │
└─────────────┘

The values of this FixedSizeListArrays are stored in a child StringArray where logical null values take up values_length slots in the array as shown in the following diagram. The logical values are shown on the left, and the actual FixedSizeListArray encoding on the right

                                ┌ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ┐
                                                        ┌ ─ ─ ─ ─ ─ ─ ─ ─┐    
 ┌─────────────┐                │     ┌───┐               ┌───┐ ┌──────┐      │
 │   [A,B]     │                      │ 1 │             │ │ 1 │ │  A   │ │ 0  
 ├─────────────┤                │     ├───┤               ├───┤ ├──────┤      │
 │    NULL     │                      │ 0 │             │ │ 1 │ │  B   │ │ 1  
 ├─────────────┤                │     ├───┤               ├───┤ ├──────┤      │
 │  [C,NULL]   │                      │ 1 │             │ │ 0 │ │ ???? │ │ 2  
 └─────────────┘                │     └───┘               ├───┤ ├──────┤      │
                                                        | │ 0 │ │ ???? │ │ 3  
 Logical Values                 │   Validity              ├───┤ ├──────┤      │
                                    (nulls)             │ │ 1 │ │  C   │ │ 4  
                                │                         ├───┤ ├──────┤      │
                                                        │ │ 0 │ │ ???? │ │ 5  
                                │                         └───┘ └──────┘      │
                                                        │     Values     │    
                                │   FixedSizeListArray        (Array)         │
                                                        └ ─ ─ ─ ─ ─ ─ ─ ─┘    
                                └ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ─ ┘

Example

// Construct a value array
let value_data = ArrayData::builder(DataType::Int32)
    .len(9)
    .add_buffer(Buffer::from_slice_ref(&[0, 1, 2, 3, 4, 5, 6, 7, 8]))
    .build()
    .unwrap();
let list_data_type = DataType::FixedSizeList(
    Arc::new(Field::new("item", DataType::Int32, false)),
    3,
);
let list_data = ArrayData::builder(list_data_type.clone())
    .len(3)
    .add_child_data(value_data.clone())
    .build()
    .unwrap();
let list_array = FixedSizeListArray::from(list_data);
let list0 = list_array.value(0);
let list1 = list_array.value(1);
let list2 = list_array.value(2);

assert_eq!( &[0, 1, 2], list0.as_any().downcast_ref::<Int32Array>().unwrap().values());
assert_eq!( &[3, 4, 5], list1.as_any().downcast_ref::<Int32Array>().unwrap().values());
assert_eq!( &[6, 7, 8], list2.as_any().downcast_ref::<Int32Array>().unwrap().values());

fixed size arrays

Implementations

impl FixedSizeListArray

pub fn new( field: FieldRef, size: i32, values: ArrayRef, nulls: Option<NullBuffer> ) -> Self

Create a new FixedSizeListArray with size element size, panicking on failure

Panics

Panics if Self::try_new returns an error

pub fn try_new( field: FieldRef, size: i32, values: ArrayRef, nulls: Option<NullBuffer> ) -> Result<Self, ArrowError>

Create a new FixedSizeListArray from the provided parts, returning an error on failure

Errors

• size < 0
• values.len() / size != nulls.len()
• values.data_type() != field.data_type()
• !field.is_nullable() && !nulls.expand(size).contains(values.logical_nulls())

pub fn new_null(field: FieldRef, size: i32, len: usize) -> Self

Create a new FixedSizeListArray of length len where all values are null

Panics

Panics if

• size < 0
• size * len would overflow usize

pub fn into_parts(self) -> (FieldRef, i32, ArrayRef, Option<NullBuffer>)

Deconstruct this array into its constituent parts

pub fn values(&self) -> &ArrayRef

Returns a reference to the values of this list.

pub fn value_type(&self) -> DataType

Returns a clone of the value type of this list.

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

Returns ith value of this list array.

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

Returns the offset for value at index i.

Note this doesn’t do any bound checking, for performance reason.

pub const fn value_length(&self) -> i32

Returns the length for an element.

All elements have the same length as the array is a fixed size.

pub fn slice(&self, offset: usize, len: usize) -> Self

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

pub fn from_iter_primitive<T, P, I>(iter: I, length: i32) -> Selfwhere T: ArrowPrimitiveType, P: IntoIterator<Item = Option<<T as ArrowPrimitiveType>::Native>>, I: IntoIterator<Item = Option<P>>,

Creates a FixedSizeListArray from an iterator of primitive values

Example

let data = vec![
   Some(vec![Some(0), Some(1), Some(2)]),
   None,
   Some(vec![Some(3), None, Some(5)]),
   Some(vec![Some(6), Some(7), Some(45)]),
];
let list_array = FixedSizeListArray::from_iter_primitive::<Int32Type, _, _>(data, 3);
println!("{:?}", list_array);

pub fn iter(&self) -> FixedSizeListIter<'_>

constructs a new iterator

Trait Implementations

impl Array for FixedSizeListArray

fn as_any(&self) -> &dyn Any

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

fn to_data(&self) -> ArrayData

Returns the underlying data of this array

fn into_data(self) -> ArrayData

Returns 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 nulls(&self) -> Option<&NullBuffer>

Returns the null buffer of this array if any

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 logical_nulls(&self) -> Option<NullBuffer>

Returns the logical null buffer of this array if any

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 physical null values in this array.

fn is_nullable(&self) -> bool

Returns false if the array is guaranteed to not contain any logical nulls

impl<'a> ArrayAccessor for &'a FixedSizeListArray

type Item = Arc<dyn Array, Global>

The Arrow type of the element being accessed.

fn value(&self, index: usize) -> Self::Item

Returns the element at index i

unsafe fn value_unchecked(&self, index: usize) -> Self::Item

Returns the element at index i

impl ArrayAccessor for FixedSizeListArray

type Item = Arc<dyn Array, Global>

The Arrow type of the element being accessed.

fn value(&self, index: usize) -> Self::Item

Returns the element at index i

unsafe fn value_unchecked(&self, index: usize) -> Self::Item

Returns the element at index i

impl Clone for FixedSizeListArray

fn clone(&self) -> FixedSizeListArray

Returns a copy of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for FixedSizeListArray

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

Formats the value using the given formatter.

impl From<ArrayData> for FixedSizeListArray

fn from(data: ArrayData) -> Self

Converts to this type from the input type.

impl From<FixedSizeListArray> for ArrayData

fn from(array: FixedSizeListArray) -> Self

Converts to this type from the input type.

impl From<FixedSizeListArray> for FixedSizeBinaryArray

Creates a FixedSizeBinaryArray from FixedSizeList<u8> array

fn from(v: FixedSizeListArray) -> Self

Converts to this type from the input type.

impl<OffsetSize: OffsetSizeTrait> From<FixedSizeListArray> for GenericListArray<OffsetSize>

fn from(value: FixedSizeListArray) -> Self

Converts to this type from the input type.

impl PartialEq<FixedSizeListArray> for FixedSizeListArray

fn eq(&self, other: &Self) -> bool

This method tests for self and other values to be equal, and is used by ==.

fn ne(&self, other: &Rhs) -> bool

This method tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.