Struct arrow_array::array::StructArray

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

An array of structs

Each child (called field) is represented by a separate array.

§Comparison with RecordBatch

Both RecordBatch and StructArray represent a collection of columns / arrays with the same length.

However, there are a couple of key differences:

StructArray is therefore a more general data container than RecordBatch, and as such code that needs to handle both will typically share an implementation in terms of StructArray and convert to/from RecordBatch as necessary.

From implementations are provided to facilitate this conversion, however, converting from a StructArray containing top-level nulls to a RecordBatch will panic, as there is no way to preserve them.

§Example: Create an array from a vector of fields

use std::sync::Arc;
use arrow_array::{Array, ArrayRef, BooleanArray, Int32Array, StructArray};
use arrow_schema::{DataType, Field};

let boolean = Arc::new(BooleanArray::from(vec![false, false, true, true]));
let int = Arc::new(Int32Array::from(vec![42, 28, 19, 31]));

let struct_array = StructArray::from(vec![
    (
        Arc::new(Field::new("b", DataType::Boolean, false)),
        boolean.clone() as ArrayRef,
    ),
    (
        Arc::new(Field::new("c", DataType::Int32, false)),
        int.clone() as ArrayRef,
    ),
]);
assert_eq!(struct_array.column(0).as_ref(), boolean.as_ref());
assert_eq!(struct_array.column(1).as_ref(), int.as_ref());
assert_eq!(4, struct_array.len());
assert_eq!(0, struct_array.null_count());
assert_eq!(0, struct_array.offset());

Implementations§

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impl StructArray

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pub fn new( fields: Fields, arrays: Vec<ArrayRef>, nulls: Option<NullBuffer>, ) -> Self

Create a new StructArray from the provided parts, panicking on failure

§Panics

Panics if Self::try_new returns an error

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pub fn try_new( fields: Fields, arrays: Vec<ArrayRef>, nulls: Option<NullBuffer>, ) -> Result<Self, ArrowError>

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

§Errors

Errors if

  • fields.len() != arrays.len()
  • fields[i].data_type() != arrays[i].data_type()
  • arrays[i].len() != arrays[j].len()
  • arrays[i].len() != nulls.len()
  • !fields[i].is_nullable() && !nulls.contains(arrays[i].nulls())
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pub fn new_null(fields: Fields, len: usize) -> Self

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

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pub unsafe fn new_unchecked( fields: Fields, arrays: Vec<ArrayRef>, nulls: Option<NullBuffer>, ) -> Self

Create a new StructArray from the provided parts without validation

§Safety

Safe if Self::new would not panic with the given arguments

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pub fn new_empty_fields(len: usize, nulls: Option<NullBuffer>) -> Self

Create a new StructArray containing no fields

§Panics

If len != nulls.len()

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pub fn into_parts(self) -> (Fields, Vec<ArrayRef>, Option<NullBuffer>)

Deconstruct this array into its constituent parts

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pub fn column(&self, pos: usize) -> &ArrayRef

Returns the field at pos.

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pub fn num_columns(&self) -> usize

Return the number of fields in this struct array

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pub fn columns(&self) -> &[ArrayRef]

Returns the fields of the struct array

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pub fn columns_ref(&self) -> Vec<ArrayRef>

👎Deprecated: Use columns().to_vec()

Returns child array refs of the struct array

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

Return field names in this struct array

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pub fn fields(&self) -> &Fields

Returns the Fields of this StructArray

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pub fn column_by_name(&self, column_name: &str) -> Option<&ArrayRef>

Return child array whose field name equals to column_name

Note: A schema can currently have duplicate field names, in which case the first field will always be selected. This issue will be addressed in ARROW-11178

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

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

Trait Implementations§

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impl Array for StructArray

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fn as_any(&self) -> &dyn Any

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) -> ArrayRef

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 Clone for StructArray

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fn clone(&self) -> StructArray

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 StructArray

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

Formats the value using the given formatter. Read more
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impl From<&StructArray> for RecordBatch

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fn from(struct_array: &StructArray) -> Self

Converts to this type from the input type.
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impl From<(Vec<(Arc<Field>, Arc<dyn Array>)>, Buffer)> for StructArray

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fn from(pair: (Vec<(FieldRef, ArrayRef)>, Buffer)) -> Self

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

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fn from(data: ArrayData) -> Self

Converts to this type from the input type.
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impl From<RecordBatch> for StructArray

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fn from(value: RecordBatch) -> Self

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

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fn from(array: StructArray) -> Self

Converts to this type from the input type.
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impl From<StructArray> for RecordBatch

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fn from(value: StructArray) -> Self

Converts to this type from the input type.
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impl From<Vec<(Arc<Field>, Arc<dyn Array>)>> for StructArray

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fn from(v: Vec<(FieldRef, ArrayRef)>) -> Self

Converts to this type from the input type.
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impl Index<&str> for StructArray

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fn index(&self, name: &str) -> &Self::Output

Get a reference to a column’s array by name.

Note: A schema can currently have duplicate field names, in which case the first field will always be selected. This issue will be addressed in ARROW-11178

§Panics

Panics if the name is not in the schema.

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type Output = Arc<dyn Array>

The returned type after indexing.
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impl PartialEq for StructArray

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fn eq(&self, other: &Self) -> 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 TryFrom<Vec<(&str, Arc<dyn Array>)>> for StructArray

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fn try_from(values: Vec<(&str, ArrayRef)>) -> Result<Self, ArrowError>

builds a StructArray from a vector of names and arrays.

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type Error = ArrowError

The type returned in the event of a conversion error.

Auto Trait Implementations§

Blanket Implementations§

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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.