javascript – Google图表堆叠列的JSON格式

我有如下数据：

           store 1   Store 2
store_id   walk-ins  walk-ins
morning      20        25
noon         35        40
night        50        55

图表堆叠每行的值有20个商店.

谷歌图表文档告诉我数据数组如下所示：

var data = google.visualization.arrayToDataTable([
        ['Stores', 'Store 1', 'Store 2', 'Store 3', 'Store 4', ... ],
        ['morning', 10, 24, 20, 32, 18, 5, ...],
        ['noon', 16, 22, 23, 30, 16, 9, ...],
        ['night', 28, 19, 29, 30, 12, 13, ...],
      ]);

我通过My​​sql脚本/服务器PHP脚本获取数据. JSON应该是什么样的？ MySQL查询的json_encode($data)返回如下;

[{“store_name”：“Store 1”,“Time”：“Morning”,“count”：“17”},…]

但图表没有加载,并给我一条消息“表没有列”.

我按如下方式加载JSON：

var url =  '/url/updatedata.PHP?var=querytype';
    jQuery.getJSON( url, function(Json) {

    // Create and populate the data table.
    var data = new google.visualization.DataTable(Json);
....

堆积柱形图的JSON结构是什么？

谢谢！

解决方法:

事实证明,您的数据映射恰好是一项非常复杂的任务.

例如,你有这个json数据：

var json = [
    {"store_name":"Store 1","Time":"Morning","count":"10"}, 
    {"store_name":"Store 1","Time":"Noon","count":"16"},  
    {"store_name":"Store 1","Time":"Night","count":"28"},    
    {"store_name":"Store 2","Time":"Morning","count":"24"}, 
    {"store_name":"Store 2","Time":"Noon","count":"22"},  
    {"store_name":"Store 2","Time":"Night","count":"19"}
];

我将underscore.js用于以下代码.它可以包括这样：

<script type="text/javascript" src="http://underscorejs.org/underscore-min.js"></script>

映射代码：

var header = _.chain(json).pluck("store_name").sort().uniq(true).value();
header.unshift("Stores");

var rows = _.chain(json)
.groupBy(function(item) { return item.Time; })
.map(function(group, key) { 
    var result = [key];
    _.each(group, function(item) { 
        result[_.indexOf(header, item.store_name)] = parseInt(item.count); 
    });
    return result; 
})
.value();

var jsonData = [header].concat(rows);

// draw chart
var data = google.visualization.arrayToDataTable(jsonData);
chart.draw(data, options);

最终的jsonData变量看起来如此：

[["Stores", "Store 1", "Store 2"], 
["Morning", 10, 24], 
["Noon", 16, 22], 
["Night", 28, 19]]

这是jsFiddle with your chart的链接.