我想制作一个<g>包含a <circle>和a 的可拖动元素，<text>但失败了。
现在我有这段代码：
var margin = {top: -5, right: -5, bottom: -5, left: -5},
width = 1960 - margin.left - margin.right,
height = 1500 - margin.top - margin.bottom;
var drag = d3.behavior.drag()
.origin(function(d) { return d; })
.on("dragstart", dragstarted)
.on("drag", dragged)
.on("dragend", dragended);
var svg = d3.select("body").append("svg")
.attr("width", width + margin.left + margin.right)
.attr("height", height + margin.top + margin.bottom);
var dotContainer = svg.append("g")
.attr("class", "dotContainer")
.datum({x:220, y:120})
.attr("x", function(d) { return d.x; })
.attr("y", …