datamodel/src/fields/field/index.js

Relational algebra compliant in-memory tabular data store

import { rowDiffsetIterator } from '../../operator/row-diffset-iterator';

/**
 * In {@link DataModel}, every tabular data consists of column, a column is stored as field.
 * Field contains all the data for a given column in an array.
 *
 * Each record consists of several fields; the fields of all records form the columns.
 * Examples of fields: name, gender, sex etc.
 *
 * In DataModel, each field can have multiple attributes which describes its data and behaviour.
 * A field can have two types of data: Measure and Dimension.
 *
 * A Dimension Field is the context on which a data is categorized and the measure is the numerical values that
 * quantify the data set.
 * In short a dimension is the lens through which you are looking at your measure data.
 *
 * Refer to {@link Schema} to get info about possible field attributes.
 *
 * @public
 * @class
 */
export default class Field {
    /**
     * Initialize a new instance.
     *
     * @public
     * @param {PartialField} partialField - The partialField instance which holds the whole data.
     * @param {string} rowDiffset - The data subset definition.
     */
    constructor (partialField, rowDiffset) {
        this.partialField = partialField;
        this.rowDiffset = rowDiffset;
    }

    /**
     * Generates the field type specific domain.
     *
     * @public
     * @abstract
     */
    domain () {
        throw new Error('Not yet implemented');
    }

    /**
     * Returns the the field schema.
     *
     * @public
     * @return {string} Returns the field schema.
     */
    schema () {
        return this.partialField.schema;
    }

    /**
     * Returns the name of the field.
     *
     * @public
     * @return {string} Returns the name of the field.
     */
    name () {
        return this.partialField.name;
    }

    /**
     * Returns the type of the field.
     *
     * @public
     * @return {string} Returns the type of the field.
     */
    type () {
        return this.partialField.schema.type;
    }

    /**
     * Returns the subtype of the field.
     *
     * @public
     * @return {string} Returns the subtype of the field.
     */
    subtype () {
        return this.partialField.schema.subtype;
    }

    /**
     * Returns the description of the field.
     *
     * @public
     * @return {string} Returns the description of the field.
     */
    description () {
        return this.partialField.schema.description;
    }

    /**
     * Returns the display name of the field.
     *
     * @public
     * @return {string} Returns the display name of the field.
     */
    displayName () {
        return this.partialField.schema.displayName || this.partialField.schema.name;
    }

    /**
     * Returns the data associated with the field.
     *
     * @public
     * @return {Array} Returns the data.
     */
    data () {
        const data = [];
        rowDiffsetIterator(this.rowDiffset, (i) => {
            data.push(this.partialField.data[i]);
        });
        return data;
    }

    /**
     * Returns the formatted version of the underlying field data.
     *
     * @public
     * @abstract
     */
    formattedData () {
        throw new Error('Not yet implemented');
    }
}