问使用JavaScript实现C3数据的数据结构/格式

EN

var data = [{
        Service: "Army",
        Permanent: 654,
        Itinerant: 754,
        Region: "Western"
    },
    {
        Service: "Air Force",
        Permanent: 9,
        Itinerant: 2,
        Region: "Eastern"
    },
    {
        Service: "Army",
        Permanent: 6,
        Itinerant: 7,
        Region: "Western"
    },
    {
        Service: "Air Force",
        Permanent: 9,
        Itinerant: 2,
        Region: "Eastern"
    }
];

var aggregates = data.map(function (o) {
    // map original objects to new ones with zeroed-out data
    return {
        Service: o.Service,
        Permanent: 0,
    }
}).filter(function (o, index, a) {
    // filter the list to have only unique `Service` properties
    var service = o.Service;
    var i;
    for (i = 0; i < a.length; i += 1) {
        if (a[i].Service === service) {
            // break out of the loop when the first matching `Service` is found.
            break;
        }
    }
    // `i` is now the index of the first matching `Service`.
    // if it's the first occurrence of that `Service`, keep it, otherwise ditch it.
    return i === index;
});

data.forEach(function (o) {
    // loop through the aggregate list and get the matching `Service` property.
    var agg = aggregates.filter(function (p) {
        return o.Service === p.Service;
    })[0]; // first element is the match.
    // sum the `Permanent` properties.
    agg.Permanent += o.Permanent;
});

// now that the data has been aggregated, transform it into the needed structure.
var c3data = aggregates.map(function (d) {
    return [d.Service, d.Permanent];
});

console.log(JSON.stringify(c3data));