JSON - 访问 JSON 数组并分配变量
JSON - Accessing JSON Array and assigning variables
>我在一个名为census.json的文件中有以下JSON：
{
"areas": [
"UnitedStates", [{
"STATEORREGION": "United States",
"1910POPULATION": 92228531,
"1920POPULATION": 106021568,
"1930POPULATION": 123202660,
"1940POPULATION": 132165129,
"1950POPULATION": 151325798,
"1960POPULATION": 179323175,
"1970POPULATION": 203211926,
"1980POPULATION": 226545805,
"1990POPULATION": 248709873,
"2000POPULATION": 281421906,
"2010POPULATION": 308745538,
"1910CHANGE": 21,
"1920CHANGE": 15,
"1930CHANGE": 16.2,
"1940CHANGE": 7.3,
"1950CHANGE": 14.5,
"1960CHANGE": 18.5,
"1970CHANGE": 13.3,
"1980CHANGE": 11.5,
"1990CHANGE": 9.8,
"2000CHANGE": 13.2,
"2010CHANGE": 9.7
}],
"Alabama", [{
"STATEORREGION": "Alabama",
"1910POPULATION": 2138093,
"1920POPULATION": 2348174,
"1930POPULATION": 2646248,
"1940POPULATION": 2832961,
"1950POPULATION": 3061743,
"1960POPULATION": 3266740,
"1970POPULATION": 3444165,
"1980POPULATION": 3893888,
"1990POPULATION": 4040587,
"2000POPULATION": 4447100,
"2010POPULATION": 4779736,
"1910CHANGE": 16.9,
"1920CHANGE": 9.8,
"1930CHANGE": 12.7,
"1940CHANGE": 7.1,
"1950CHANGE": 8.1,
"1960CHANGE": 6.7,
"1970CHANGE": 5.4,
"1980CHANGE": 13.1,
"1990CHANGE": 3.8,
"2000CHANGE": 10.1,
"2010CHANGE": 7.5
}],
"Alaska", [{
"STATEORREGION": "Alaska",
"1910POPULATION": 64356,
"1920POPULATION": 55036,
"1930POPULATION": 59278,
"1940POPULATION": 72524,
"1950POPULATION": 128643,
"1960POPULATION": 226167,
"1970POPULATION": 300382,
"1980POPULATION": 401851,
"1990POPULATION": 550043,
"2000POPULATION": 626932,
"2010POPULATION": 710231,
"1910CHANGE": 1.2,
"1920CHANGE": -14.5,
"1930CHANGE": 7.7,
"1940CHANGE": 22.3,
"1950CHANGE": 77.4,
"1960CHANGE": 75.8,
"1970CHANGE": 32.8,
"1980CHANGE": 33.8,
"1990CHANGE": 36.9,
"2000CHANGE": 14,
"2010CHANGE": 13.3
}], ]
}
我正在尝试使用以下方法访问存储在数组中的不同值：
$.getJSON("../data/census.json", function (json) {
var censusData = json;
console.log(censusData.areas);
});
这会将所有状态作为对象记录到控制台，因此我随后尝试使用以下命令下到另一个级别：
$.getJSON("../data/census.json", function (json) {
var censusData = json;
console.log(censusData.areas.UnitedStates);
});
但这返回"未定义"。 如何向下钻取另一个级别？ 理想情况下，我想访问特定年份的每个州人口，然后将其分配给我以后可以使用的变量。
这里的模式是在每个字符串名称之后，我们都有一个相关信息数组：所以你可以把它转换成一个对象，比如
var _result = {};
for ( var i=0;i<arr.length/2;i++){
_result[arr[i]] = arr[i+1];
}
然后，您可以通过字符串名称直接访问这些信息
喜欢这个
censusData.areas.UnitedStates
将在此转换后返回一个数组
目前没有第二级，因为州名及其属性之间有逗号而不是冒号：
"Alaska", [{
"STATEORREGION":"Alaska",
"1910POPULATION":64356,
...
这使得值"阿拉斯加"和属性字典在列表中相邻元素。似乎你想要的是：
"Alaska": [{
"STATEORREGION":"Alaska",
"1910POPULATION":64356,
...
您的 JSON 数据无效，请尝试此操作，
{"areas" : [
"UnitedStates", [{
"STATEORREGION":"United States",
"1910POPULATION":92228531,
"1920POPULATION":106021568,
"1930POPULATION":123202660,
"1940POPULATION":132165129,
"1950POPULATION":151325798,
"1960POPULATION":179323175,
"1970POPULATION":203211926,
"1980POPULATION":226545805,
"1990POPULATION":248709873,
"2000POPULATION":281421906,
"2010POPULATION":308745538,
"1910CHANGE":21,
"1920CHANGE":15,
"1930CHANGE":16.2,
"1940CHANGE":7.3,
"1950CHANGE":14.5,
"1960CHANGE":18.5,
"1970CHANGE":13.3,
"1980CHANGE":11.5,
"1990CHANGE":9.8,
"2000CHANGE":13.2,
"2010CHANGE":9.7
}],
"Alabama", [{
"STATEORREGION":"Alabama",
"1910POPULATION":2138093,
"1920POPULATION":2348174,
"1930POPULATION":2646248,
"1940POPULATION":2832961,
"1950POPULATION":3061743,
"1960POPULATION":3266740,
"1970POPULATION":3444165,
"1980POPULATION":3893888,
"1990POPULATION":4040587,
"2000POPULATION":4447100,
"2010POPULATION":4779736,
"1910CHANGE":16.9,
"1920CHANGE":9.8,
"1930CHANGE":12.7,
"1940CHANGE":7.1,
"1950CHANGE":8.1,
"1960CHANGE":6.7,
"1970CHANGE":5.4,
"1980CHANGE":13.1,
"1990CHANGE":3.8,
"2000CHANGE":10.1,
"2010CHANGE":7.5
}],
"Alaska", [{
"STATEORREGION":"Alaska",
"1910POPULATION":64356,
"1920POPULATION":55036,
"1930POPULATION":59278,
"1940POPULATION":72524,
"1950POPULATION":128643,
"1960POPULATION":226167,
"1970POPULATION":300382,
"1980POPULATION":401851,
"1990POPULATION":550043,
"2000POPULATION":626932,
"2010POPULATION":710231,
"1910CHANGE":1.2,
"1920CHANGE":-14.5,
"1930CHANGE":7.7,
"1940CHANGE":22.3,
"1950CHANGE":77.4,
"1960CHANGE":75.8,
"1970CHANGE":32.8,
"1980CHANGE":33.8,
"1990CHANGE":36.9,
"2000CHANGE":14,
"2010CHANGE":13.3
}]
]
}
因此，我能够通过将 JSON 的结构更改为以下内容来访问数据：
{"areas" : [
[{
"STATEORREGION":"United States",
"POPULATION1910":92228531,
"1920POPULATION":106021568,
"1930POPULATION":123202660,
"1940POPULATION":132165129,
"1950POPULATION":151325798,
"1960POPULATION":179323175,
"1970POPULATION":203211926,
"1980POPULATION":226545805,
"1990POPULATION":248709873,
"2000POPULATION":281421906,
"2010POPULATION":308745538,
"1910CHANGE":21,
"1920CHANGE":15,
"1930CHANGE":16.2,
"1940CHANGE":7.3,
"1950CHANGE":14.5,
"1960CHANGE":18.5,
"1970CHANGE":13.3,
"1980CHANGE":11.5,
"1990CHANGE":9.8,
"2000CHANGE":13.2,
"2010CHANGE":9.7
}],
[{
"STATEORREGION":"Alabama",
"1910POPULATION":2138093,
"1920POPULATION":2348174,
"1930POPULATION":2646248,
"1940POPULATION":2832961,
"1950POPULATION":3061743,
"1960POPULATION":3266740,
"1970POPULATION":3444165,
"1980POPULATION":3893888,
"1990POPULATION":4040587,
"2000POPULATION":4447100,
"2010POPULATION":4779736,
"1910CHANGE":16.9,
"1920CHANGE":9.8,
"1930CHANGE":12.7,
"1940CHANGE":7.1,
"1950CHANGE":8.1,
"1960CHANGE":6.7,
"1970CHANGE":5.4,
"1980CHANGE":13.1,
"1990CHANGE":3.8,
"2000CHANGE":10.1,
"2010CHANGE":7.5
}],
[{
"STATEORREGION":"Alaska",
"1910POPULATION":64356,
"1920POPULATION":55036,
"1930POPULATION":59278,
"1940POPULATION":72524,
"1950POPULATION":128643,
"1960POPULATION":226167,
"1970POPULATION":300382,
"1980POPULATION":401851,
"1990POPULATION":550043,
"2000POPULATION":626932,
"2010POPULATION":710231,
"1910CHANGE":1.2,
"1920CHANGE":-14.5,
"1930CHANGE":7.7,
"1940CHANGE":22.3,
"1950CHANGE":77.4,
"1960CHANGE":75.8,
"1970CHANGE":32.8,
"1980CHANGE":33.8,
"1990CHANGE":36.9,
"2000CHANGE":14,
"2010CHANGE":13.3
}]
]
}
然后我使用了：
$.getJSON( "../data/census.json", function( json ) {
var censusData = json;
console.log(censusData.areas[0][0].POPULATION1910);
});
另请注意，我必须将1910POPULATION更改为POPULATION1910才能访问它而不会出错。 可能比更改每个状态的每个键名称更好的方法。
当我想访问下一个状态时，我只是将censusData[0][0]更改为censusData[1][0]等等。
字符串"United States"是列表中的第一个元素。
美国的数据是censusData.areas[1].JSON的结构看起来有点奇怪。
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