Javascript，JSON，D3并访问嵌套变量以创建饼图

Question

I need to iterate over an array's field in my JSON document. The field I would like is "total" in the energy array. Here is my sample 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

}

]

I want to create a pie chart for each date, so each pie chart will have "coal", "wind" and "nuclear" totals. I am obviously not accessing the data properly because the chart I am creating is coal = 25, wind = 50, and nuclear = 100.

Here is the snippet from my javascript:

//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

I can see how to access a specific value in the field I'm looking for (data[0].energy[0].total) which would be 5. But how can I iterate over all the totals in energy[0] and then energy[1], etc? I played around with the forEach function but I couldn't get it to work. I hope my question makes sense. Any help or pointing in the right direction would be very appreciated. I've been looking at this code for awhile without a break through.

Answer 1

Not sure if this is what you are looking for or not....

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')
    }
}

Alternative since you use foreach:

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

fiddle https://jsfiddle.net/6cf31spn/