Struct Map 

pub struct Map<K, V, const SORTED: bool = false>(/* private fields */);

Wrapper denoting an Arrow MapArray column with entries (K, V).

• Keys are non-nullable by Arrow spec.
• Values are non-nullable for Map<K, V, SORTED> and nullable for Map<K, Option<V>, SORTED>.
• Column-level nullability is expressed with Option<Map<...>>.

Implementations

impl<K, V, const SORTED: bool> Map<K, V, SORTED>

pub fn new(entries: Vec<(K, V)>) -> Self

Construct a new map from a vector of (key, value) pairs.

Examples found in repository

examples/11_map.rs (line 18)

fn main() {
    // Standalone Map column
    let mut b = <Map<String, i32> as ArrowBinding>::new_builder(0);
    <Map<String, i32> as ArrowBinding>::append_value(
        &mut b,
        &Map::new(vec![("a".to_string(), 1), ("b".to_string(), 2)]),
    );
    <Map<String, i32> as ArrowBinding>::append_null(&mut b);
    let a = <Map<String, i32> as ArrowBinding>::finish(b);
    println!(
        "standalone map rows={}, entries={}",
        a.len(),
        a.entries().len()
    );

    // Sorted keys example (keys_sorted = true)
    let dt_sorted = <Map<String, i32, true> as ArrowBinding>::data_type();
    println!("sorted map datatype = {dt_sorted:?}");

    // OrderedMap using BTreeMap row layout
    let mut ord = BTreeMap::new();
    ord.insert("b".to_string(), 2);
    ord.insert("a".to_string(), 1);
    let mut ob = <OrderedMap<String, i32> as ArrowBinding>::new_builder(0);
    <OrderedMap<String, i32> as ArrowBinding>::append_value(&mut ob, &OrderedMap::new(ord));
    let oa = <OrderedMap<String, i32> as ArrowBinding>::finish(ob);
    println!("ordered map entries={}", oa.entries().len());

    // In a Record
    let rows = vec![
        Row {
            id: 1,
            tags: Map::new(vec![("x".to_string(), 10)]),
            notes: Some(Map::new(vec![
                ("hello".to_string(), Some("world".to_string())),
                ("empty".to_string(), None),
            ])),
        },
        Row {
            id: 2,
            tags: Map::new(vec![]),
            notes: None,
        },
    ];
    let mut rb = <Row as typed_arrow::schema::BuildRows>::new_builders(rows.len());
    rb.append_rows(rows);
    let arrays = rb.finish();
    let batch = arrays.into_record_batch();
    println!(
        "record rows={}, fields={}",
        batch.num_rows(),
        batch.schema().fields().len()
    );
}

pub fn entries(&self) -> &Vec<(K, V)>

Borrow the underlying (key, value) entries.

pub fn into_inner(self) -> Vec<(K, V)>

Consume and return the underlying (key, value) entries.

Trait Implementations

impl<K, V, const SORTED: bool> ArrowBinding for Map<K, Option<V>, SORTED>

where K: ArrowBinding, V: ArrowBinding, <K as ArrowBinding>::Builder: ArrayBuilder, <V as ArrowBinding>::Builder: ArrayBuilder,

type Builder = MapBuilder<<K as ArrowBinding>::Builder, <V as ArrowBinding>::Builder>

Concrete Arrow builder type used for this Rust type.

type Array = MapArray

Concrete Arrow array type produced by finish.

fn data_type() -> DataType

The Arrow DataType corresponding to this Rust type.

fn new_builder(_capacity: usize) -> Self::Builder

Create a new builder with an optional capacity hint.

fn append_value(b: &mut Self::Builder, v: &Self)

Append a non-null value to the builder.

fn append_null(b: &mut Self::Builder)

Append a null to the builder.

fn finish(b: Self::Builder) -> Self::Array

Finish the builder and produce a typed Arrow array.

impl<K, V, const SORTED: bool> ArrowBinding for Map<K, V, SORTED>

where K: ArrowBinding, V: ArrowBinding, <K as ArrowBinding>::Builder: ArrayBuilder, <V as ArrowBinding>::Builder: ArrayBuilder,

type Builder = MapBuilder<<K as ArrowBinding>::Builder, <V as ArrowBinding>::Builder>

Concrete Arrow builder type used for this Rust type.

type Array = MapArray

Concrete Arrow array type produced by finish.

fn data_type() -> DataType

The Arrow DataType corresponding to this Rust type.

fn new_builder(_capacity: usize) -> Self::Builder

Create a new builder with an optional capacity hint.

fn append_value(b: &mut Self::Builder, v: &Self)

Append a non-null value to the builder.

fn append_null(b: &mut Self::Builder)

Append a null to the builder.

fn finish(b: Self::Builder) -> Self::Array

Finish the builder and produce a typed Arrow array.

impl<K, V, const SORTED: bool> From<Vec<(K, V)>> for Map<K, V, SORTED>

fn from(entries: Vec<(K, V)>) -> Self

Convert a vector of (key, value) pairs into a Map.

impl<K, V, const SORTED: bool> FromIterator<(K, V)> for Map<K, V, SORTED>

fn from_iter<I: IntoIterator<Item = (K, V)>>(iter: I) -> Self

Collect an iterator of (key, value) pairs into a Map.