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RecordBatch

info

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

A RecordBatch is a fixed-width row set of equal-length child vectors.

Overview​

Use table.batches[i] from a Table, or deserialize IPC input to get RecordBatch instances.

import {Table, Field, Int32, Utf8, makeTable} from 'apache-arrow';

const table = makeTable({
  id: [1, 2, 3],
  label: ['a', 'b', 'c']
});

const batch = table.batches[0];

Usage​

import {makeTable, Field, Int32, Utf8} from 'apache-arrow';

const table = makeTable({
  id: [1, 2, 3],
  label: ['a', 'b', 'c']
});
const batch = table.batches[0];
console.log(batch?.numRows, batch?.schema?.length);
import {makeVector, Struct, Field, Int32, Utf8} from 'apache-arrow';

const batch = makeTable({
  id: [1, 2],
  label: ['x', 'y']
}).batches[0];
for (const row of batch) {
  console.log(row.id, row.label);
}

Constructors​

new RecordBatch<T extends TypeMap = any>(columns: { [P in keyof T]: Data<T[P]> })

new RecordBatch<T extends TypeMap = any>(schema: Schema<T>, data?: Data<Struct<T>>).
Build a record batch from a schema and backing struct data.

Members​

schema: Schema (readonly)​

Batch schema.

data: Data<Struct> (readonly)​

Flattened row-major backing data.

numCols: number (readonly)​

Number of columns.

numRows: number (readonly)​

Number of rows.

nullCount: number (readonly)​

Number of null rows.

Methods​

isValid(index: number): boolean​

Returns whether row at index is non-null.

get(index: number): StructRowProxy<T> | null​

Returns row data at index.

at(index: number): StructRowProxy<T> | null​

Returns row data at index, with negative indexes counting from the end.

set(index: number, value: Struct<T>['TValue']): void​

Assigns one row value at index.

indexOf(element: Struct<T>['TValue'], offset?: number): number​

Finds the first row matching element.

[Symbol.iterator](): IterableIterator<StructRowProxy<T>>​

Iterates rows in row order.

toArray(): StructRowProxy<T>[]​

Converts all rows into a JS array.

toString(): string​

Returns a human-readable row dump.

concat(...others: RecordBatch<T>[]): Table<T>​

Returns a single table by concatenating same-schema record batches.

slice(begin?: number, end?: number): RecordBatch<T>​

Returns a row-range view, end-exclusive.

getChild(name: keyof T): Vector | null​

Returns child vector by field name.

getChildAt(index: number): Vector | null​

Returns child vector by field position.

setChild(name: keyof T, child: Vector): RecordBatch​

Returns a new batch with a named child replaced.

setChildAt(index: number, child?: Vector | null): RecordBatch​

Returns a new batch with a child replaced at index.

select<K extends keyof T = any>(columnNames: K[]): RecordBatch<{ [P in K]: T[P] }>​

Returns a new batch with only selected names.

selectAt<K extends T = any>(columnIndices: number[]): RecordBatch<{ [P in keyof K]: K[P] }>​

Returns a new batch with only selected indexes.