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Data

info

This page is aligned to Apache Arrow JS v21.x (apache-arrow).

Untyped storage backing for Vector.

Think of Data as a chunk: typed arrays and metadata for one contiguous segment.

Usage​

import {makeData, Int32} from 'apache-arrow';

const data = makeData({
  type: new Int32(),
  data: new Int32Array([1, 2, 3]),
  length: 3,
  nullCount: 0
});
import {makeData, Int32} from 'apache-arrow';

const data = makeData({type: new Int32(), length: 2, nullCount: 0, data: new Int32Array([1, 2])});
const copy = data.slice(0, 1);
console.log(copy.length, copy.getValid(0));

Members​

type: T​

The logical DataType.

length: number​

Number of logical elements.

offset: number​

Logical offset into the underlying buffers.

stride: number​

Elements per logical slot.

children: Data[]​

Nested child data.

dictionary?: Vector​

Optional dictionary backing (for Dictionary type only).

values: TBuffer[BufferType.DATA]​

Primary values buffer.

typeIds: TBuffer[BufferType.TYPE]​

Dictionary/union type id buffer.

nullBitmap: TBuffer[BufferType.VALIDITY]​

Validity bitmask.

valueOffsets: TBuffer[BufferType.OFFSET]​

Offset buffers for variable-width types.

ArrayType: T['ArrayType']​

Physical JS typed array constructor.

typeId: T['TType']​

Underlying type enum id.

buffers: Buffers<T>​

Named tuple view of data buffers.

nullable: boolean​

Whether the element type can represent null.

byteLength: number​

Byte size across buffers.

nullCount: number​

Computed number of null rows.

Factory usage​

Data objects are created via makeData() in the apache-arrow exports.

Methods​

constructor(type: T, offset: number, length: number, nullCount?: number, buffers?: Partial<Buffers<T>> | Data<T>, children?: Data[], dictionary?: Vector)​

Low-level constructor used for manual Data assembly and advanced integrations.

getValid(index: number): boolean​

Returns whether element is non-null.

setValid(index: number, value: boolean): boolean​

Set nullability state for one element.

clone<R extends DataType = T>(type?: R, offset?: number, length?: number, nullCount?: number, buffers?: Buffers<R>, children?: Data[]): Data<R>​

Clone and optionally override metadata.

slice(offset: number, length: number): Data<T>​

Create a sliced data instance.