wink-statistics/src/accessor.js

Fast and Numerically Stable Statistical Analysis Utilities

//     wink-statistics
//     Fast and Numerically Stable Statistical Analysis Utilities.
//
//     Copyright (C) GRAYPE Systems Private Limited
//
//     This file is part of “wink-statistics”.
//
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//
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// ## Private

// ### accessor
/**
 * Returns the value from `data` that is accessed via `accessor`.
 *
 * @private
 *
 * @param {number} data from where a value is extracted using `accessor`.
 * @param {(string|function)} [accessor=undefined] It should be a property-name
 * contained in `data` or function; `undefined` means the `data` is returned as-is.
 * @return {number} — value from `data` according to `accessor`.
 *
*/
var value = function ( data, accessor ) {
  if ( accessor === undefined ) return data;
  if ( typeof accessor === 'string' || typeof accessor === 'number' ) return data[ accessor ];
  if ( typeof accessor === 'function' ) return accessor( data );
  throw Error( 'accessor: expecting undefined, string, number, or function, instead found: ' + ( typeof accessor ) );
}; // accessor()

module.exports = value;