Struct arrow::array::array::FixedSizeListArray

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pub struct FixedSizeListArray { /* private fields */ }
Expand description

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§

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impl FixedSizeListArray

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pub fn new( field: Arc<Field>, size: i32, values: Arc<dyn Array>, nulls: Option<NullBuffer>, ) -> FixedSizeListArray

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

§Panics

Panics if Self::try_new returns an error

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pub fn try_new( field: Arc<Field>, size: i32, values: Arc<dyn Array>, nulls: Option<NullBuffer>, ) -> Result<FixedSizeListArray, 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())
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pub fn new_null(field: Arc<Field>, size: i32, len: usize) -> FixedSizeListArray

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

§Panics

Panics if

  • size < 0
  • size * len would overflow usize
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pub fn into_parts(self) -> (Arc<Field>, i32, Arc<dyn Array>, Option<NullBuffer>)

Deconstruct this array into its constituent parts

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pub fn values(&self) -> &Arc<dyn Array>

Returns a reference to the values of this list.

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pub fn value_type(&self) -> DataType

Returns a clone of the value type of this list.

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pub fn value(&self, i: usize) -> Arc<dyn Array>

Returns ith value of this list array.

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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.

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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.

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

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

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pub fn from_iter_primitive<T, P, I>(iter: I, length: i32) -> FixedSizeListArray
where 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);
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pub fn iter(&self) -> ArrayIter<&FixedSizeListArray>

constructs a new iterator

Trait Implementations§

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impl Array for FixedSizeListArray

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fn as_any(&self) -> &(dyn Any + 'static)

Returns the array as Any so that it can be downcasted to a specific implementation. Read more
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fn to_data(&self) -> ArrayData

Returns the underlying data of this array
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fn into_data(self) -> ArrayData

Returns the underlying data of this array Read more
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fn data_type(&self) -> &DataType

Returns a reference to the DataType of this array. Read more
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fn slice(&self, offset: usize, length: usize) -> Arc<dyn Array>

Returns a zero-copy slice of this array with the indicated offset and length. Read more
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fn len(&self) -> usize

Returns the length (i.e., number of elements) of this array. Read more
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fn is_empty(&self) -> bool

Returns whether this array is empty. Read more
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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. Read more
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fn nulls(&self) -> Option<&NullBuffer>

Returns the null buffer of this array if any. Read more
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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. Note that this does not always correspond to the exact memory usage of an array, since multiple arrays can share the same buffers or slices thereof.
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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.
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fn logical_nulls(&self) -> Option<NullBuffer>

Returns a potentially computed NullBuffer that represents the logical null values of this array, if any. Read more
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fn is_null(&self, index: usize) -> bool

Returns whether the element at index is null according to Array::nulls Read more
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fn is_valid(&self, index: usize) -> bool

Returns whether the element at index is not null, the opposite of Self::is_null. Read more
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fn null_count(&self) -> usize

Returns the total number of physical null values in this array. Read more
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fn is_nullable(&self) -> bool

Returns false if the array is guaranteed to not contain any logical nulls Read more
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impl<'a> ArrayAccessor for &'a FixedSizeListArray

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type Item = Arc<dyn Array>

The Arrow type of the element being accessed.
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fn value(&self, index: usize) -> <&'a FixedSizeListArray as ArrayAccessor>::Item

Returns the element at index i Read more
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unsafe fn value_unchecked( &self, index: usize, ) -> <&'a FixedSizeListArray as ArrayAccessor>::Item

Returns the element at index i Read more
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impl ArrayAccessor for FixedSizeListArray

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type Item = Arc<dyn Array>

The Arrow type of the element being accessed.
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fn value(&self, index: usize) -> <FixedSizeListArray as ArrayAccessor>::Item

Returns the element at index i Read more
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unsafe fn value_unchecked( &self, index: usize, ) -> <FixedSizeListArray as ArrayAccessor>::Item

Returns the element at index i Read more
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impl Clone for FixedSizeListArray

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fn clone(&self) -> FixedSizeListArray

Returns a copy of the value. Read more
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fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source. Read more
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impl Debug for FixedSizeListArray

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

Formats the value using the given formatter. Read more
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impl From<ArrayData> for FixedSizeListArray

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fn from(data: ArrayData) -> FixedSizeListArray

Converts to this type from the input type.
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impl From<FixedSizeListArray> for ArrayData

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fn from(array: FixedSizeListArray) -> ArrayData

Converts to this type from the input type.
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impl From<FixedSizeListArray> for FixedSizeBinaryArray

Creates a FixedSizeBinaryArray from FixedSizeList<u8> array

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fn from(v: FixedSizeListArray) -> FixedSizeBinaryArray

Converts to this type from the input type.
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impl<OffsetSize> From<FixedSizeListArray> for GenericListArray<OffsetSize>
where OffsetSize: OffsetSizeTrait,

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fn from(value: FixedSizeListArray) -> GenericListArray<OffsetSize>

Converts to this type from the input type.
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impl PartialEq for FixedSizeListArray

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

Tests for self and other values to be equal, and is used by ==.
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fn ne(&self, other: &Rhs) -> bool

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

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impl<T> Any for T
where T: 'static + ?Sized,

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fn type_id(&self) -> TypeId

Gets the TypeId of self. Read more
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impl<T> Borrow<T> for T
where T: ?Sized,

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fn borrow(&self) -> &T

Immutably borrows from an owned value. Read more
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impl<T> BorrowMut<T> for T
where T: ?Sized,

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fn borrow_mut(&mut self) -> &mut T

Mutably borrows from an owned value. Read more
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impl<T> CloneToUninit for T
where T: Clone,

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default unsafe fn clone_to_uninit(&self, dst: *mut T)

🔬This is a nightly-only experimental API. (clone_to_uninit)
Performs copy-assignment from self to dst. Read more
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impl<T> Datum for T
where T: Array,

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fn get(&self) -> (&dyn Array, bool)

Returns the value for this Datum and a boolean indicating if the value is scalar
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impl<T> From<T> for T

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fn from(t: T) -> T

Returns the argument unchanged.

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impl<T, U> Into<U> for T
where U: From<T>,

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fn into(self) -> U

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

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impl<T> ToOwned for T
where T: Clone,

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type Owned = T

The resulting type after obtaining ownership.
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fn to_owned(&self) -> T

Creates owned data from borrowed data, usually by cloning. Read more
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fn clone_into(&self, target: &mut T)

Uses borrowed data to replace owned data, usually by cloning. Read more
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impl<T, U> TryFrom<U> for T
where U: Into<T>,

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type Error = Infallible

The type returned in the event of a conversion error.
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fn try_from(value: U) -> Result<T, <T as TryFrom<U>>::Error>

Performs the conversion.
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impl<T, U> TryInto<U> for T
where U: TryFrom<T>,

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type Error = <U as TryFrom<T>>::Error

The type returned in the event of a conversion error.
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fn try_into(self) -> Result<U, <U as TryFrom<T>>::Error>

Performs the conversion.