dd_xcx/node_modules/@antv/scale/lib/pow.js

function _inheritsLoose(subClass, superClass) { subClass.prototype = Object.create(superClass.prototype); subClass.prototype.constructor = subClass; subClass.__proto__ = superClass; }

/**
 * @fileOverview 使用pow进行度量计算
 * @author dxq613@gmail.com
 */
var Base = require('./base');

var Linear = require('./linear'); // 求以a为次幂，结果为b的基数，如 x^^a = b;求x


function calBase(a, b) {
  var e = Math.E;
  var value = Math.pow(e, Math.log(b) / a); // 使用换底公式求底

  return value;
}
/**
 * 度量的Pow计算
 * @class Scale.Log
 */


var Pow =
/*#__PURE__*/
function (_Linear) {
  _inheritsLoose(Pow, _Linear);

  function Pow() {
    return _Linear.apply(this, arguments) || this;
  }

  var _proto = Pow.prototype;

  _proto._initDefaultCfg = function _initDefaultCfg() {
    _Linear.prototype._initDefaultCfg.call(this);

    this.type = 'pow';
    /**
     * @override
     * pow 的坐标点的个数控制在10个以下
     * @type {Number}
     */

    this.tickCount = 10;
    /**
     * 进行pow计算的基数
     * @type {Number}
     */

    this.exponent = 2;
  }
  /**
   * @override
   */
  ;

  _proto.calculateTicks = function calculateTicks() {
    var self = this;
    var exponent = self.exponent;
    var min;
    var max = Math.ceil(calBase(exponent, self.max));

    if (self.min >= 0) {
      min = Math.floor(calBase(exponent, self.min));
    } else {
      min = 0;
    }

    if (min > max) {
      var tmp = max;
      max = min;
      min = tmp;
    }

    var count = max - min;
    var tickCount = self.tickCount;
    var avg = Math.ceil(count / tickCount);
    var ticks = [];

    for (var i = min; i < max + avg; i = i + avg) {
      ticks.push(Math.pow(i, exponent));
    }

    return ticks;
  } // 获取度量计算时，value占的定义域百分比
  ;

  _proto._getScalePercent = function _getScalePercent(value) {
    var max = this.max;
    var min = this.min;

    if (max === min) {
      return 0;
    }

    var exponent = this.exponent;
    var percent = (calBase(exponent, value) - calBase(exponent, min)) / (calBase(exponent, max) - calBase(exponent, min));
    return percent;
  }
  /**
   * @override
   */
  ;

  _proto.scale = function scale(value) {
    var percent = this._getScalePercent(value);

    var rangeMin = this.rangeMin();
    var rangeMax = this.rangeMax();
    return rangeMin + percent * (rangeMax - rangeMin);
  }
  /**
   * @override
   */
  ;

  _proto.invert = function invert(value) {
    var percent = (value - this.rangeMin()) / (this.rangeMax() - this.rangeMin());
    var exponent = this.exponent;
    var max = calBase(exponent, this.max);
    var min = calBase(exponent, this.min);
    var tmp = percent * (max - min) + min;
    return Math.pow(tmp, exponent);
  };

  return Pow;
}(Linear);

Base.Pow = Pow;
module.exports = Pow;