d3.js——弦图的绘制

首先我们要明白弦图所要表达的意思是什么？比如我们有以下一组关于地区人口的数据：

var city_name = ["北京","上海","广州","深圳","香港"];
var population = [
    [1000,3015,4567,1234,3714],
    [3214,2000,2060,124,3234],
    [8761,6545,3000,8045,647],
    [3211,1067,3214,4000,1006],
    [2146,1034,6745,4764,5000]
];va