function retrieveRaw(option) {
	        var ret = {};
	        each(
	            ['start', 'end', 'startValue', 'endValue', 'throttle'],
	            function (name) {
	                option.hasOwnProperty(name) && (ret[name] = option[name]);
	            }
	        );
	        return ret;
	    }
Only calculate by given range and this._dataExtent, do not change anything.

@param {Object} opt
@param {number} [opt.start]
@param {number} [opt.end]
@param {number} [opt.startValue]
@param {number} [opt.endValue]