arquero
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Query processing and transformation of array-backed data tables.
105 lines (104 loc) • 4.65 kB
TypeScript
/**
* Options for fixed width file parsing.
* @typedef {object} FixedParseOptions
* @property {[number, number][]} [positions] Array of start, end indices for
* fixed-width columns. Specifying extact positions supports extraction of
* a selected subset of columns.
* @property {number[]} [widths] Array of fixed column widths. This option is
* ignored if the positions property is specified.
* @property {string[]} [names] An array of column names. The array length
* should match the length of the positions array. If not specified or
* shorter than the positions array, default column names are generated.
* @property {string} [decimal='.'] Single-character numeric decimal separator.
* @property {number} [skip=0] The number of lines to skip before reading data.
* @property {string} [comment] A string used to identify comment lines. Any
* lines that start with the comment pattern are skipped.
* @property {boolean} [autoType=true] Flag for automatic type inference.
* @property {number} [autoMax=1000] Maximum number of initial values to use
* for type inference.
* @property {Record<string, (value: string) => any>} [parse] Object of
* column parsing options. The object keys should be column names. The object
* values should be parsing functions that transform values upon input.
*/
/**
* Parse a fixed-width file (FWF) string into a table. By default, automatic
* type inference is performed for input values; string values that match the
* ISO standard date format are parsed into JavaScript Date objects. To
* disable this behavior, set the autoType option to false. To perform custom
* parsing of input column values, use the parse option.
* @param {string} input The input text.
* @param {FixedParseOptions} [options] The formatting options.
* @return {ColumnTable} An Arquero table.
*/
export function fromFixed(input: string, options?: FixedParseOptions): ColumnTable;
/**
* Parse a fixed-width file (FWF) stream into a table. By default, automatic
* type inference is performed for input values; string values that match the
* ISO standard date format are parsed into JavaScript Date objects. To
* disable this behavior, set the autoType option to false. To perform custom
* parsing of input column values, use the parse option.
* @param {ReadableStream<string>} stream The input stream.
* @param {FixedParseOptions} [options] The formatting options.
* @return {Promise<ColumnTable>} A Promise to an Arquero table.
*/
export function fromFixedStream(stream: ReadableStream<string>, options?: FixedParseOptions): Promise<ColumnTable>;
/**
* Load a fixed width file from a URL and return a Promise for an Arquero table.
* @param {string} path The URL or file path to load.
* @param {import('./types.js').LoadOptions & FixedParseOptions} [options]
* Fixed width parse options.
* @return {Promise<ColumnTable>} A Promise to an Arquero table.
* @example aq.loadFixedWidth('data/table.txt', { names: ['name', 'city', state'], widths: [10, 20, 2] })
*/
export function loadFixed(path: string, options?: import("./types.js").LoadOptions & FixedParseOptions): Promise<ColumnTable>;
/**
* Options for fixed width file parsing.
*/
export type FixedParseOptions = {
/**
* Array of start, end indices for
* fixed-width columns. Specifying extact positions supports extraction of
* a selected subset of columns.
*/
positions?: [number, number][];
/**
* Array of fixed column widths. This option is
* ignored if the positions property is specified.
*/
widths?: number[];
/**
* An array of column names. The array length
* should match the length of the positions array. If not specified or
* shorter than the positions array, default column names are generated.
*/
names?: string[];
/**
* Single-character numeric decimal separator.
*/
decimal?: string;
/**
* The number of lines to skip before reading data.
*/
skip?: number;
/**
* A string used to identify comment lines. Any
* lines that start with the comment pattern are skipped.
*/
comment?: string;
/**
* Flag for automatic type inference.
*/
autoType?: boolean;
/**
* Maximum number of initial values to use
* for type inference.
*/
autoMax?: number;
/**
* Object of
* column parsing options. The object keys should be column names. The object
* values should be parsing functions that transform values upon input.
*/
parse?: Record<string, (value: string) => any>;
};
import { ColumnTable } from '../table/ColumnTable.js';