function getRandom(pre, next) {
	return pre + (Math.random() * (next - pre)) * 0.01;
}
var num = 200,arr = [] , x = getRandom(113.953640, 116.953640),y = getRandom(22.537018, 25.537018);

arr.push({x:x,y:y});

//阿基米德螺旋
var a =1,b =0.1,fix = 0.001;

for(var i=0;i<num;i++){
	var angle = 0.1 * i;
	var _x = x + (a + b * angle) * Math.cos(angle) * fix;
	var _y = y + (a + b * angle) * Math.sin(angle) * fix;
	arr.push({x:_x,y:_y });
}

console.log(JSON.stringify(arr));