例如: 10000电单付款10001水单付款10002煤气账单付款10003电费帐单付款10001水单付款10001水单付款我的代码是: d3.csv("activities.csv", function(error,data) { //fetching and storing the activities as key and their individual count as value countByActivties= d3.nest() .key(function(d) { retu...