从dataset1到dataset2的图形栏D3js

Question

这是我的代码，我花了很多时间在我创建的2个数据之间进行转换：dataset1和dataset2？

  var dataset1 = [3,3,7,10];
    var dataset2 = [8,7,5,20];

var sel1 = d3.select("body")
           .append("svg")
           .attr("width","100%")
           .attr("height","100%")

var sel2 = sel1.selectAll("rect")
               .data(dataset1)

               .enter()
               .append("rect")
               .attr("width",function(d,i){return 40})
               .attr("height",function(d,i){return d*10})
               .attr("x",function(d,i){return ((i*40)+i)+30})
               .attr("y",function(d,i){return 400-(d*10)})
            sel1.selectAll("rect")
                .data(dataset2)
                .tansition()
                .duration(300)
                .attr("height",function(d,i){return d*10})
                .attr("y",function(d,i){return 400-(d*10)})

谁能帮助我更好地使代码变白，非常感谢