将天气预报数据载入气象图表资料机
我对编程很陌生。所以请容忍我。我想用图表显示实时天气预报数据，特别是气温和降水量与时段的关系。我从openweathermap.org获取的天气数据。示例："https://samples.openweathermap.org/data/2.5/forecast?q=M%C3%BCnchen,DE&appid=b6907d289e10d714a6e88b30761fae22“，我希望在下面的标准图表示例中使用它。
var chart = AmCharts.makeChart("chartdiv", {
"type": "serial",
"theme": "dark",
"dataLoader": {
"url": "data/serial2.json",
"showErrors": true,
"complete": function ( chart ) {
console.log( "Loading complete" );
},
"load": function ( options, chart ) {
console.log( "File loaded: ", options.url );
},
"error": function ( options, chart ) {
console.log( "Error occured loading file: ", options.url );
}
},
"categoryField": "year",
"startDuration": 1,
"rotate": false,
"categoryAxis": {
"gridPosition": "start"
},
"valueAxes": [{
"position": "top",
"title": "Million USD",
"minorGridEnabled": true
}],
"graphs": [{
"type": "column",
"title": "Income",
"valueField": "income",
"fillAlphas":1,
"balloonText": "<span style='font-size:13px;'>[[title]] in [[category]]:<b>[[value]]</b></span>"
}, {
"type": "line",
"title": "Expenses",
"valueField": "expenses",
"lineThickness": 2,
"bullet": "round",
"balloonText": "<span style='font-size:13px;'>[[title]] in [[category]]:<b>[[value]]</b></span>"
}],
"legend": {
"useGraphSettings": true
},
"creditsPosition": "top-right",
"responsive": {
"enabled": true
}
});
function reloadData() {
chart.dataLoader.loadData();
}
我所面临的问题是，天气数据是一个复杂的json，我不能简单地用温度和降水来代替地震场和数值场。
有人能指导我怎么做吗？任何线索都会被发现。谢谢!
回答 1
Stack Overflow用户
发布于 2018-10-09 14:51:16
考虑到源JSON格式复杂，不能直接使用AmCharts，您必须使用dataLoader的postProcess回调来获取响应并使其适应您的需要。如果您查看openweathermap示例API响应文档，您将看到它映射出每个字段以及它们对应的内容。感兴趣的主要性质有：main.temp、dt、rain.3h和snow.3h。您需要为每个点提取这些信息，并将其分配给您的数组。您的API响应在list数组下有每个点，因此您需要遍历它。
下面是postProcess方法的样子：
"dataLoader": {
"url": "YOUR API URL HERE",
"postProcess": function(jsonData) {
var newData = []; //dataProvider for your chart
//loop through your API response's list array for the data you need
jsonData.list.forEach(function(periodInfo) {
//set up the data point with the converted timestamp,
//converted temperature, and placeholder for precipitation
var dataPoint = {
"date": periodInfo.dt * 1000, //convert to milliseconds
"temperature": periodInfo.main.temp - 273.15, //convert kelvin to celsius
"precipitation": 0
};
//check if we have a value for rain precipitation before adding it to our precipitation property
if (periodInfo.rain !== undefined && periodInfo.rain['3h'] !== undefined) {
dataPoint.precipitation += periodInfo.rain['3h'];
}
//check if we have a value for snow precipitation before adding it in
if (periodInfo.snow !== undefined && periodInfo.snow['3h'] !== undefined) {
dataPoint.precipitation += periodInfo.snow['3h'];
}
//finally, add it to your new data array
newData.push(dataPoint);
});
//return the new array to be assigned to the chart's dataProvider
return newData;
}
},现在您已经映射了数据，您必须更新makeChart调用以查找这些属性，方法是使用相应的valueField属性(temperature和precipitation)创建graph对象，将categoryField设置为date，并创建一个启用parseDates的categoryAxis，并创建一个minPeriod设置为hh，因为数据是每小时一次的。您还可能希望为您的降水值创建第二个值轴。
下面是更新的makeChart属性的片段：
//create value axes for both temperature and precip values
"valueAxes": [{
"id": "temperature",
"title": "Temperature (C)"
}, {
"id": "precipitation",
"title": "Precipitation (mm)",
"position": "right"
}],
"synchronizeGrid": true, //make sure the grids from both axes are synchronized
"graphs": [{
"bullet": "round",
"valueField": "temperature"
},{
"fillAlphas": 0.9,
"lineAlpha": 0.2,
"type": "column",
"valueField": "precipitation",
"valueAxis": "precipitation" //plot this against the precipitation value axis
}],
"categoryField": "date",
"categoryAxis": {
"parseDates": true,
"minPeriod": "hh" //make sure we plot hourly data correctly
},下面是一个使用上述API响应的静态JSON文件的演示来说明这一点。我添加了一些其他的生活质量设置，如光标和设置精度。我建议查看AmCharts API文档以获得更多信息。
https://stackoverflow.com/questions/52716398
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