Question

我正在尝试使用ammap绘制线条而且我无法为起点和终点生成坐标数组。我必须使用具有case_study作为密钥的json数组，如下所示

var data = {
  "countries_involved": [
    {"c_id": 6, "country": "India", "longitude": "21", "latitude": "78.0000", "involvement": 3, "case_study": 4},
    {"c_id": 7, "country": "Canada", "longitude": "62", "latitude": "105.3809", "involvement": 3, "case_study": 4}, 
    {"c_id": 8, "country": "Comoros", "longitude": "12", "latitude": "44.2333", "involvement": 1, "case_study": 5},
    {"c_id": 9, "country": "Madagascar", "longitude": "20", "latitude": "47.0000", "involvement": 1, "case_study": 5},
    {"c_id": 10, "country": "Mauritius", "longitude": "20", "latitude": "57.5000", "involvement": 1, "case_study": 5}
  ],
  "country_details": [
    {"name": "Kenya", "longitude": "-1", "latitude": "36.8000", "case_study": 4},
    {"name": "Kenya", "longitude": "-1", "latitude": "36.8000", "case_study": 5}
  ]
};

我正在使用jquery过滤器以下列格式返回数据

{longitudes: [country_details.longitude,countries_involved.longitude], latitudes: [country_details.latitude,countries_involved.latitude],}

这是我在for循环中的函数

for (var i = 0; i < data.country_details.length; i++)
{
  var obj = {
    id: data.country_details[i]['name'].replace(/\s+/g, ''),
    color: "#000000",
    svgPath: targetSVG,
    title: data.country_details[i]['country'],
    latitude: data.country_details[i]['longitude'],
    longitude: data.country_details[i]['latitude'],
    scale: 1.5,
    zoomLevel: 2.74,
    lines: data.countries_involved.filter(function(involved) {
      return involved.case_study === data.country_details[i].case_study
    }).map(function(item) {
      return {latitudes: [data.country_details[i].latitude, item.latitude], longitudes: [data.country_details[i].longitude, item.longitude]}
    })
  };
}

但是，我只得到一个仅包含起点但不是终点的数组，这意味着item.latitude和item.longitude没有评估。有人可以帮帮忙吗？

Answer 1

在这段代码中：

data.countries_involved.filter(function(involved){
    return involved.case_study === data.country_details[i].case_study
}).map(function(item){
    return {
        latitudes: [data.country_details[i].latitude, item.latitude], 
        longitudes: [data.country_details[i].longitude, item.longitude]
    };
});

未定义变量'i'。

我相信在内置javascript数组'map'和'filter'函数的情况下，您正在迭代的集合中的索引将作为 second 参数传递。因此，将'i'声明为这两行中的第二个参数：

data.countries_involved.filter(function(involved, i){
// and:
}).map(function(item, i){

编辑： Array.prototype.map和Array.prototype.filter并非在所有浏览器中都可用。要使用jQuery map和filter，请执行以下操作：

$($.grep(data.countries_involved, function(involved){
    return involved.case_study === data.country_details[i].case_study
})).map(function(idx, item){
    return {
        latitudes: [data.country_details[i].latitude, item.latitude], 
        longitudes: [data.country_details[i].longitude, item.longitude]
    };
}).get()

Javascript数组助手

1 个答案: