@uwdata/mosaic-core/dist/src/util/to-data-columns.js

Scalable and extensible linked data views.

import { isArrowTable } from './is-arrow-table.js';
/**
 * Convert input data to a set of column arrays.
 * @param data The input data.
 * @returns An object with named column arrays.
 */
export function toDataColumns(data) {
    if (isArrowTable(data)) {
        return arrowToColumns(data);
    }
    else if (Array.isArray(data)) {
        return arrayToColumns(data);
    }
    else {
        throw new Error('Unrecognized data format.');
    }
}
/**
 * Convert an Arrow table to a set of column arrays.
 * @param data An Arrow Table.
 * @returns An object with named column arrays.
 */
function arrowToColumns(data) {
    const { numRows } = data;
    return { numRows, columns: data.toColumns() };
}
/**
 * Convert an array of values to a set of column arrays.
 * If the array values are objects, build out named columns.
 * We use the keys of the first object as the column names.
 * Otherwise, use a special "values" array.
 * @param data An array of data objects.
 * @returns An object with named column arrays.
 */
function arrayToColumns(data) {
    const numRows = data.length;
    if (typeof data[0] === 'object') {
        const names = numRows ? Object.keys(data[0]) : [];
        const columns = {};
        if (names.length > 0) {
            names.forEach(name => {
                columns[name] = data.map(d => d[name]);
            });
        }
        return { numRows, columns };
    }
    else {
        return { numRows, values: data };
    }
}
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