Question

我需要在JSON文档中迭代数组的字段。我想要的领域是能量阵列中的“总数”。这是我的示例json doc。

[
    {
        "time": "01/01/2000",
        "country": "USA",
        "energy":
         [
            {"type": "coal", "total": 25, "color": "black"},
            {"type": "wind", "total": 25, "color": "blue"},
            {"type": "nuclear", "total": 25, "color": "yellow"}
         ],
        "lat": 180,
        "lon": 225

},
    {
    "time": "01/02/2000",
    "country": "USA",
    "energy":
     [
        {"type": "coal", "total": 50, "color": "black"},
        {"type": "wind", "total": 50, "color": "blue"},
        {"type": "nuclear", "total": 50, "color": "yellow"}
     ],
    "lat": 180,
    "lon": 225

},
        {
    "time": "01/03/2000",
    "country": "USA",
    "energy":
     [
        {"type": "coal", "total": 100, "color": "black"},
        {"type": "wind", "total": 100, "color": "blue"},
        {"type": "nuclear", "total": 100, "color": "yellow"}
     ],
    "lat": 180,
    "lon": 225

}

我想为每个日期创建一个饼图，因此每个饼图将具有“煤”，“风”和“核”总数。我显然没有正确访问数据，因为我创建的图表是煤= 25，风= 50，核= 100。

以下是我的javascript：

的片段

//beginning of test data for pie2
var color = d3.scale.ordinal()
.range(["#98abc5", "#8a89a6", "#7b6888", "#6b486b", "#a05d56", "#d0743c", "#ff8c00"]);

d3.json("energyFormat.json",function (data) {  
    data.forEach(function(d, i){
        console.log("what is d.total: " + d.energy[i].total)
        d.energy[i]=d.energy[i++]

    })

var arc = d3.svg.arc()
.outerRadius(40)
.innerRadius(30);

var pie = d3.layout.pie()
.sort(null)
.value(function (d, i) {
//console.log("is d.total :" + d.energy[i].total )
return d.energy[i].total;

});

var g = svg.selectAll("arc")
    .data(data)
    .enter().append("g")
    .attr("transform", function(d, i){
        //console.log("what is d.lon: " + d.lon)
        //console.log("what is d.energy: " + d.energy[i])
     return "translate(" + d.lon + "," + d.lat + ")" });

g.append("path")
    .data(pie(data))
    .attr("d", arc)    
    .style("fill", function (d, i) {
        //console.log("is this color " + d.data.energy[i].color)
    return d.data.energy[i].color;
        });

g.append("text")
    .data(pie(data))
    .attr("transform", function (d) {
        return "translate(" + arc.centroid(d) + ")";
    })
    .attr("dy", ".35em")
    .style("text-anchor", "middle")
    .style("fill", "white")
    .style("font-size","12px")
    .text(function (d, i) {
        console.log(d.data.energy[i].total);
        return d.data.energy[i].type;
    });
});

//end of test data for pie2

我可以看到如何访问我正在寻找的字段中的特定值（data [0] .energy [0] .total），这将是5.但是我如何迭代能量中的所有总数[ 0]然后能量[1]等？我玩过forEach功能，但我无法让它工作。我希望我的问题有道理。任何帮助或指向正确的方向将非常感激。我一直在看这段代码而没有突破。

Answer 1

不确定这是否是您要找的......

for(var i = 0; i < data.length; i++) {
    for(var j = 0; j < data[i].energy.length; j++) {
        console.log(data[i].energy[j].total, 'energy total')
    }
}

替代方法，因为您使用foreach：

data.forEach(function(element, index){
    element.energy.forEach(function(element, index) {
        console.log(element.total, 'energy total')
    })
})

小提琴https://jsfiddle.net/6cf31spn/

Javascript，JSON，D3和访问嵌套变量以创建饼图

1 个答案: