code: function (point, clamp) {
          var coord = this.pointToCoord(point);
          return [
              this._radiusAxis.radiusToData(coord[0], clamp),
              this._angleAxis.angleToData(coord[1], clamp)
          ];
      }
docs: Convert a (x, y) point to data
  @param {Array.<number>} point
  @param {boolean} [clamp=false]
  @return {Array.<number>}