D3 - 將數據標籤添加到一個簡單的條形圖

Question

我知道這很容易，我在這個論壇以及其他網站也看到一些例子，但我簡單無法弄清楚。

我是新使用D3庫來生成圖表。我試圖通過創建條形圖來學習。

我的問題是如何將數據標籤添加到圖表中？

以下是我的代碼。

然後我有我的JS：

var chartwidth = 800; 
    var chartheight = 600; 

    var data = [ 
     {"Start_Dt":"Jan 15","UnitName":"Unit 1","ProgramName":"ProgramName 1","AttendCnt":159,"NewcomerCnt":10} 
     , {"Start_Dt":"Jan 22","UnitName":"Unit 2","ProgramName":"ProgramName 2","AttendCnt":178,"NewcomerCnt":5} 
     , {"Start_Dt":"Feb 14","UnitName":"Unit 2","ProgramName":"ProgramName 3","AttendCnt":240,"NewcomerCnt":46} 
     , {"Start_Dt":"Feb 19","UnitName":"Unit 1","ProgramName":"ProgramName 4","AttendCnt":201,"NewcomerCnt":10} 
     , {"Start_Dt":"Feb 26","UnitName":"Unit 2","ProgramName":"ProgramName 5","AttendCnt":177,"NewcomerCnt":7} 
     , {"Start_Dt":"Mar 12","UnitName":"Unit N","ProgramName":"ProgramName N","AttendCnt":184,"NewcomerCnt":3} 
    ];       

    var margin = {top: 20, right: 20, bottom: 300, left: 40}, 
     width = chartwidth - margin.left - margin.right, 
     height = chartheight - margin.top - margin.bottom; 

    var formatPercent = d3.format(".0%"); 
    var formatTime = d3.time.format("%e %B"); 

    var x = d3.scale.ordinal() 
    .rangeRoundBands([0, width], .1); 

    var x2 = d3.scale.ordinal() 
    .rangeBands([0, width], 0); 

    var y = d3.scale.linear() 
    .range([height, 0]); 

    var xAxis = d3.svg.axis() 
    .scale(x) 
    .orient("bottom"); 

    var yAxis = d3.svg.axis() 
    .scale(y) 
    .orient("left"); 

    var svg = d3.select(".chart").append("svg") 
    .attr("width", width + margin.left + margin.right) 
    .attr("height", height + margin.top + margin.bottom) 
    .append("g") 
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")"); 


    data.forEach(function(d) { 
     d.AttendCnt = +d.AttendCnt; 
    }); 

    x.domain(data.map(function(d) { return d.Start_Dt + " " + d.ProgramName; })); 
    y.domain([0, d3.max(data, function(d) { return d.AttendCnt; })]); 

    //Create X Axis 
    svg.append("g") 
     .attr("class", "x axis") 
     .attr("transform", "translate(0," + height + ")") 
     .call(xAxis)       
     .selectAll("text") 
     .style("text-anchor", "end") 
     .attr("dx", "-.8em") 
     .attr("dy", ".15em") 
     .attr("transform", "rotate(-65)") 
     .append("text") 
     .attr("y", 25) 
     .attr("x",x.rangeBand()/2) 
     .style("text-anchor", "middle") 
     .style("font-size", "20px") 
     .style("color", "black") 
     .text(function(d,i) { return "xxx"; }); 

    //Create Y Axis 
    svg.append("g") 
     .attr("class", "y axis") 
     .call(yAxis) 
     .append("text") 
     .attr("transform", "rotate(-90)") 
     .attr("y", 0) 
     .attr("dy", ".71em") 
     .style("text-anchor", "end") 
     .text("Attendance"); 

    svg.selectAll(".bar") 
     .data(data)         
     .enter().append("rect") 
     .attr("class", "bar") 
     .attr("x", function(d) { return x(d.Start_Dt + " " + d.ProgramName); }) 
     .attr("width", x.rangeBand()) 
     .attr("y", function(d) { return y(d.AttendCnt); }) 
     .attr("height", function(d) { return height - y(d.AttendCnt); }); 

Before

After

如何修改代碼以取得我想要的結果？ TKS

Answer 1

我沒有測試的代碼，但它可能是這樣的：

svg.selectAll(".barText") 
     .data(data)         
     .enter().append("text") 
     .attr("class", "barText") 
     .attr("x", function(d) { return x(d.Start_Dt + " " + d.ProgramName); }) 
     .attr("y", function(d) { return height - y(d.AttendCnt); }) 
     .text(function(d) { return d.AttendCnt; }) 
     ; 

希望它可以幫助