改变弧度的方法

smooth为true的时候smoothness:0.2,可以设置曲线的弧度，另外data中也可单独设置曲线的弧度

    markLine : {
                            smooth:true,
                            smoothness:0.2,  // 在这可以设置线的弧度
                            effect : {
                                show: true,
                                scaleSize: 2,
                                period: 15,
                                color: 'rgba(255,255,255,0.7)',
                                shadowBlur: 5
                            },
                            itemStyle : {
                                normal: {
                                    label:{
                                        show:true,
                                        color: '#333333',
                                         formatter: ''
                                        },
                                    silent:true,
                                    borderWidth:1,
                                    lineStyle: {
                                        type: 'solid',
                                        shadowBlur: 3
                                    }
                                }
                            },
                            data : [
                                [{name:'北京'}, {name:'华盛顿',value:25,smoothness:0.4}],
                                [{name:'上海'}, {name:'华盛顿',value:90,smoothness:0.4}],
                                [{name:'北京'}, {name:'纽约',value:80,smoothness:0.4}],
                                [{name:'北京'}, {name:'亚特兰大',value:70,smoothness:0.4}],
                                [{name:'上海'}, {name:'纽约',value:60,smoothness:0.4}],
                                [{name:'北京'}, {name:'波士顿',value:50,smoothness:0.4}],
                                [{name:'北京'}, {name:'芝加哥',value:40,smoothness:0.4}],
                                [{name:'包头'}, {name:'亚特兰大',value:30,smoothness:0.4}],
                                [{name:'乌鲁木齐'}, {name:'纽约',value:20,smoothness:0.4}],
                                [{name:'包头'}, {name:'华盛顿',value:75,smoothness:0.4}]
                            ]
                        },