项目场景：

通过Echarts修改南丁格尔图js文件，修改轮盘颜色。使项目更加美观

文本标签自定义

问题描述

不知道为什么自定义函数使饼图图形上的文本标签label标签显示在内部且，获得对应标签的数据。使用自定义函数formatter的参数是ar，为什么是ar这个参数，而且神奇的是

ar.name和ar.value就可以获得标签名和标签数据！！我以为是随便起的变量名字而已

实际上我错了，用param就不行了，我以为这参数随意的。

var ec_world2 = echarts.init(document.getElementById('w2'), "dark");//自己写var ec_world2_Option = {title: {show:true,text: '海外疫情分析',subtext: '实时数据更新\n—— by 有梦想的薯条',textStyle:{fontSize:28,fontWeight:"bolder",},textAlign:"left",padding:[150,500,750,500],//上，右，下，左subtextStyle: {fontSize: 13,fontStyle:"oblique",left:"center",lineHeight:20,},},legend: {show:"true",left: "70%",top:"50%",itemGap:15,icon:"circle"},toolbox: {show: true,orient:'horizontal',feature: {mark: { show: true },dataView: { show: true, readOnly: false },restore: { show: true },saveAsImage: { show: true },}},labelLine: {show: false},series: [{name: 'Nightingale Chart',type: 'pie',lengendHoverLink:true,selectedMode:'multiple',selectedOffset:24,clockwise:false,left:'1%',label:{show:true,position:'inside',formatter(ar){return ar.name+":"+ar.value}},radius: [15, 470],center: ['50%', '71%'],roseType: 'area',itemStyle: {borderRadius:5},data: [],color: ["RGB(175,7,82)","RGB(200,13,66)","RGB(224,10,46)","RGB(219,94,30)","RGB(213,105,48)","RGB(243,123,7)","RGB(240,131,38)","RGB(221,184,41)","RGB(221,210,41)","RGB(195,222,41)","RGB(136,219,40)","RGB(122,241,18)","RGB(55,233,16)","RGB(39,227,21)","RGB(29,225,51)","RGB(29,208,46)","RGB(48,197,54)","RGB(57,187,91)","RGB(90,186,164)","RGB(89,139,146)","RGB(89,121,146)"],}]
};
ec_world2.setOption(ec_world2_Option);

效果如图所示