vis-utils/lib/findEqualSorted.js

Utility functions for data visualization

'use strict';

Object.defineProperty(exports, "__esModule", {
  value: true
});
exports.default = findEqualSorted;

var _binarySearch = require('binary-search');

var _binarySearch2 = _interopRequireDefault(_binarySearch);

function _interopRequireDefault(obj) { return obj && obj.__esModule ? obj : { default: obj }; }

/**
 * Helper function to find the item that matches this value.
 * Since it assumes the data is sorted, it does a binary search O(log n)
 *
 * @param {Array} array the input array to search
 * @param {Number} value the value to match against (typically pixels)
 * @param {Function} accessor applied to each item in the array to get equivalent
 *   value to compare against
 * @return {Any} The item in the array that has this value or null if not found
 */
function findEqualSorted(array, value) {
  var accessor = arguments.length > 2 && arguments[2] !== undefined ? arguments[2] : function (d) {
    return d;
  };

  // binary search uses the value directly in comparisons, so make sure not to
  // run the accessor on it
  var index = (0, _binarySearch2.default)(array, value, function (a, b) {
    var aValue = a === value ? value : accessor(a);
    var bValue = b === value ? value : accessor(b);
    return aValue - bValue;
  });
  return array[index];
}