[−][src]Module arrow::array
The central type in Apache Arrow are arrays, represented
by the Array trait.
An array represents a known-length sequence of values all
having the same type.
Internally, those values are represented by one or several
buffers, the number and meaning
of which depend on the array’s data type, as documented in
the Arrow data layout specification.
For example, the type Int16Array represents an Apache
Arrow array of 16-bit integers.
Those buffers consist of the value data itself and an optional bitmap buffer that indicates which array entries are null values. The bitmap buffer can be entirely omitted if the array is known to have zero null values.
There are concrete implementations of this trait for each data type, that help you access individual values of the array.
Building an Array
Arrow's Arrays are immutable, but there is the trait
ArrayBuilder
that helps you with constructing new Arrays. As with the
Array trait, there are builder implementations for all
concrete array types.
Example
extern crate arrow; use arrow::array::{Int16Array, PrimitiveArrayOps}; // Create a new builder with a capacity of 100 let mut builder = Int16Array::builder(100); // Append a single primitive value builder.append_value(1).unwrap(); // Append a null value builder.append_null().unwrap(); // Append a slice of primitive values builder.append_slice(&[2, 3, 4]).unwrap(); // Build the array let array = builder.finish(); assert_eq!( 5, array.len(), "The array has 5 values, counting the null value" ); assert_eq!(2, array.value(2), "Get the value with index 2"); assert_eq!( array.value_slice(3, 2), &[3, 4], "Get slice of len 2 starting at idx 3" )
Structs
| ArrayData | An generic representation of Arrow array data which encapsulates common attributes and
operations for Arrow array. Specific operations for different arrays types (e.g.,
primitive, list, struct) are implemented in |
| ArrayDataBuilder | Builder for |
| BinaryBuilder | Array builder for |
| BufferBuilder | Builder for creating a |
| DictionaryArray | A dictionary array where each element is a single value indexed by an integer key. This is mostly used to represent strings or a limited set of primitive types as integers, for example when doing NLP analysis or representing chromosomes by name. |
| FixedSizeBinaryArray | A type of |
| FixedSizeBinaryBuilder | |
| FixedSizeListArray | A list array where each element is a fixed-size sequence of values with the same type whose maximum length is represented by a i32. |
| FixedSizeListBuilder | Array builder for |
| GenericBinaryArray | |
| GenericListArray | |
| GenericStringArray | Generic struct for [Large]StringArray |
| LargeBinaryBuilder | |
| LargeListBuilder | Array builder for |
| LargeStringBuilder | |
| ListBuilder | Array builder for |
| NullArray | An Array where all elements are nulls |
| PrimitiveArray | Array whose elements are of primitive types. |
| PrimitiveBuilder | Array builder for fixed-width primitive types |
| PrimitiveDictionaryBuilder | Array builder for |
| PrimitiveIter | an iterator that returns Some(T) or None, that can be used on any non-boolean PrimitiveArray |
| StringBuilder | |
| StringDictionaryBuilder | Array builder for |
| StructArray | A nested array type where each child (called field) is represented by a separate array. |
| StructBuilder | Array builder for Struct types. |
| UnionArray | An Array that can represent slots of varying types |
| UnionBuilder | Builder type for creating a new |
Traits
| Array | Trait for dealing with different types of array at runtime when the type of the array is not known in advance. |
| ArrayBuilder | Trait for dealing with different array builders at runtime |
| ArrayEqual | Trait for |
| BufferBuilderTrait | Trait for simplifying the construction of |
| JsonEqual | Trait for comparing arrow array with json array |
| OffsetSizeTrait | trait declaring an offset size, relevant for i32 vs i64 array types. |
| OrdArray | Trait for Arrays that can be sorted |
| PrimitiveArrayOps | Common operations for primitive types, including numeric types and boolean type. |
| StringOffsetSizeTrait | Like OffsetSizeTrait, but specialized for Strings |
Functions
| as_boolean_array | Force downcast ArrayRef to BooleanArray |
| as_dictionary_array | Force downcast ArrayRef to DictionaryArray |
| as_null_array | Force downcast ArrayRef to NullArray |
| as_ordarray | Convert ArrayRef to OrdArray trait object |
| as_primitive_array | Force downcast ArrayRef to PrimitiveArray |
| as_string_array | Force downcast ArrayRef to StringArray |
| make_array | Constructs an array using the input |