Struct arrow_array::builder::GenericByteDictionaryBuilder

pub struct GenericByteDictionaryBuilder<K, T>where
    K: ArrowDictionaryKeyType,
    T: ByteArrayType,{ /* private fields */ }

Generic array builder for DictionaryArray that stores generic byte values. For example to map a set of byte indices to String values. Note that the use of a HashMap here will not scale to very large arrays or result in an ordered dictionary.

Implementations

impl<K, T> GenericByteDictionaryBuilder<K, T>where
    K: ArrowDictionaryKeyType,
    T: ByteArrayType,

pub fn new() -> Self

Creates a new GenericByteDictionaryBuilder

pub fn with_capacity(
    keys_capacity: usize,
    value_capacity: usize,
    data_capacity: usize
) -> Self

Creates a new GenericByteDictionaryBuilder with the provided capacities

keys_capacity: the number of keys, i.e. length of array to build value_capacity: the number of distinct dictionary values, i.e. size of dictionary data_capacity: the total number of bytes of all distinct bytes in the dictionary

pub fn new_with_dictionary(
    keys_capacity: usize,
    dictionary_values: &GenericByteArray<T>
) -> Result<Self, ArrowError>

Creates a new GenericByteDictionaryBuilder from a keys capacity and a dictionary which is initialized with the given values. The indices of those dictionary values are used as keys.

Example

let dictionary_values = StringArray::from(vec![None, Some("abc"), Some("def")]);

let mut builder = StringDictionaryBuilder::new_with_dictionary(3, &dictionary_values).unwrap();
builder.append("def").unwrap();
builder.append_null();
builder.append("abc").unwrap();

let dictionary_array = builder.finish();

let keys = dictionary_array.keys();

assert_eq!(keys, &Int16Array::from(vec![Some(2), None, Some(1)]));

impl<K, T> GenericByteDictionaryBuilder<K, T>where
    K: ArrowDictionaryKeyType,
    T: ByteArrayType,

pub fn append(
    &mut self,
    value: impl AsRef<T::Native>
) -> Result<K::Native, ArrowError>

Append a primitive value to the array. Return an existing index if already present in the values array or a new index if the value is appended to the values array.

Returns an error if the new index would overflow the key type.

pub fn append_null(&mut self)

Appends a null slot into the builder

pub fn finish(&mut self) -> DictionaryArray<K>

Builds the DictionaryArray and reset this builder.

pub fn finish_cloned(&self) -> DictionaryArray<K>

Builds the DictionaryArray without resetting the builder.

Trait Implementations

impl<K, T> ArrayBuilder for GenericByteDictionaryBuilder<K, T>where
    K: ArrowDictionaryKeyType,
    T: ByteArrayType,

fn as_any(&self) -> &dyn Any

Returns the builder as an non-mutable Any reference.

fn as_any_mut(&mut self) -> &mut dyn Any

Returns the builder as an mutable Any reference.

fn into_box_any(self: Box<Self>) -> Box<dyn Any>

Returns the boxed builder as a box of Any.

fn len(&self) -> usize

Returns the number of array slots in the builder

fn is_empty(&self) -> bool

Returns whether the number of array slots is zero

fn finish(&mut self) -> ArrayRef

Builds the array and reset this builder.

fn finish_cloned(&self) -> ArrayRef

Builds the array without resetting the builder.

impl<K, T> Debug for GenericByteDictionaryBuilder<K, T>where
    K: ArrowDictionaryKeyType + Debug,
    T: ByteArrayType + Debug,
    K::Native: Debug,

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

Formats the value using the given formatter.

impl<K, T> Default for GenericByteDictionaryBuilder<K, T>where
    K: ArrowDictionaryKeyType,
    T: ByteArrayType,

fn default() -> Self

Returns the “default value” for a type.