javascript - 为 flot 图形数组格式化 json 数据

标签 javascript php json flot

我使用以下 php 代码将温度传感器数据从 MySQL 数据库提取到 php 文件中:

<?php
$hostname = 'xxxxx';
$username = 'xxxxx';
$password = 'xxxxx';
$dbname="measurements";
$usertable="temperature";

try {
$dbh = new PDO("mysql:host=$hostname;dbname=measurements", 
                           $username, $password);
/*** The SQL SELECT statement ***/
$sth = $dbh->prepare("
   SELECT
   ROUND(AVG(`temperature`),1) AS temperature,
   TIMESTAMP(LEFT(`dtg`,16)) AS dtg
   FROM `temperature`
   GROUP BY LEFT(`dtg`,16)
   ORDER BY `dtg` DESC
   LIMIT 0,800
");
$sth->execute();

/* Fetch all of the remaining rows in the result set */
$result = $sth->fetchAll(PDO::FETCH_ASSOC);
/*** close the database connection ***/
$dbh = null;

}
catch(PDOException $e)
{
    echo $e->getMessage();
}

function make_pair($date, $amount) {
return array($date, $amount);
}
$json_data = json_encode($result, JSON_NUMERIC_CHECK); 
?>

然后我使用 javascript 在浮点图中绘制此数据:

 <script type="text/javascript">
//put array into javascript variable

var dataset1 = <?php echo json_encode($result); ?>;

//plot
$(document).ready(function () {
    $.plot($("#placeholder"),  dataset1  );
});

</script>

当我在浏览器中打开 php 文件并查看 javscript 控制台时，我可以看到数据正常通过并作为变量 dataset1 保存

看起来像这样:

//put array into javascript variable

var dataset1 = [{"temperature":"19.6","dtg":"2016-07-28 12:53:00"},{"temperature":"19.5","dtg":"2016-07-28 12:52:00"},{"temperature":"19.5","dtg":"2016-07-28 12:51:00"},{"temperature":"19.6","dtg":"2016-07-28 12:50:00"},{"temperature":"19.6","dtg":"2016-07-28 12:49:00"},{"temperature":"19.6","dtg":"2016-07-28 12:48:00"},{"temperature":"19.6","dtg":"2016-07-28 12:47:00"},{"temperature":"19.6","dtg":"2016-07-28 12:46:00"},{"temperature":"19.6","dtg":"2016-07-28 12:45:00"},{"temperature":"19.6","dtg":"2016-07-28 12:44:00"},{"temperature":"19.7","dtg":"2016-07-28 12:43:00"},{"temperature":"19.7","dtg":"2016-07-28 12:42:00"},{"temperature":"19.7","dtg":"2016-07-28 12:41:00"},{"temperature":"19.7","dtg":"2016-07-28 12:40:00"},{"temperature":"19.7","dtg":"2016-07-28 12:39:00"},{"temperature":"19.7","dtg":"2016-07-28 12:38:00"},{"temperature":"19.8","dtg":"2016-07-28 12:37:00"},{"temperature":"19.8","dtg":"2016-07-28 12:36:00"},{"temperature":"19.8","dtg":"2016-07-28 12:35:00"},{"temperature":"19.8","dtg":"2016-07-28 12:34:00"},{"temperature":"19.8","dtg":"2016-07-28 12:33:00"},{"temperature":"19.8","dtg":"2016-07-28 12:32:00"},{"temperature":"19.8","dtg":"2016-07-28 12:31:00"},{"temperature":"19.8","dtg":"2016-07-28 12:30:00"},{"temperature":"19.9","dtg":"2016-07-28 12:29:00"},{"temperature":"19.9","dtg":"2016-07-28 12:28:00"},{"temperature":"19.9","dtg":"2016-07-28 12:27:00"},{"temperature":"19.9","dtg":"2016-07-28 12:26:00"},{"temperature":"19.9","dtg":"2016-07-28 12:25:00"},{"temperature":"19.9","dtg":"2016-07-28 12:24:00"},{"temperature":"20.0","dtg":"2016-07-28 12:23:00"},{"temperature":"20.0","dtg":"2016-07-28 12:22:00"},{"temperature":"20.1","dtg":"2016-07-28 12:21:00"},{"temperature":"20.1","dtg":"2016-07-28 12:20:00"},{"temperature":"20.1","dtg":"2016-07-28 12:19:00"},{"temperature":"20.0","dtg":"2016-07-28 12:18:00"},{"temperature":"20.0","dtg":"2016-07-28 12:17:00"},{"temperature":"20.0","dtg":"2016-07-28 12:16:00"},{"temperature":"20.0","dtg":"2016-07-28 12:15:00"},{"temperature":"20.0","dtg":"2016-07-28 12:14:00"},{"temperature":"20.0","dtg":"2016-07-28 12:13:00"},{"temperature":"20.0","dtg":"2016-07-28 12:12:00"},{"temperature":"20.0","dtg":"2016-07-28 12:11:00"},{"temperature":"19.9","dtg":"2016-07-28 12:10:00"},{"temperature":"20.0","dtg":"2016-07-28 12:09:00"},{"temperature":"20.0","dtg":"2016-07-28 12:08:00"},{"temperature":"20.0","dtg":"2016-07-28 12:07:00"},{"temperature":"20.0","dtg":"2016-07-28 12:06:00"},{"temperature":"19.9","dtg":"2016-07-28 12:05:00"},{"temperature":"19.9","dtg":"2016-07-28 12:04:00"},{"temperature":"19.9","dtg":"2016-07-28 12:03:00"},{"temperature":"19.9","dtg":"2016-07-28 12:02:00"},{"temperature":"19.9","dtg":"2016-07-28 12:01:00"},{"temperature":"19.9","dtg":"2016-07-28 12:00:00"},{"temperature":"19.9","dtg":"2016-07-28 11:59:00"},{"temperature":"19.9","dtg":"2016-07-28 11:58:00"},{"temperature":"19.8","dtg":"2016-07-28 11:57:00"},{"temperature":"19.8","dtg":"2016-07-28 11:56:00"},{"temperature":"19.8","dtg":"2016-07-28 11:55:00"},{"temperature":"19.8","dtg":"2016-07-28 11:54:00"},{"temperature":"19.8","dtg":"2016-07-28 11:53:00"},{"temperature":"19.7","dtg":"2016-07-28 11:52:00"},{"temperature":"19.7","dtg":"2016-07-28 11:51:00"},{"temperature":"19.7","dtg":"2016-07-28 11:50:00"},{"temperature":"19.7","dtg":"2016-07-28 11:49:00"},{"temperature":"19.7","dtg":"2016-07-28 11:48:00"},{"temperature":"19.7","dtg":"2016-07-28 11:47:00"},{"temperature":"19.6","dtg":"2016-07-28 11:46:00"},{"temperature":"19.7","dtg":"2016-07-28 11:45:00"},{"temperature":"19.6","dtg":"2016-07-28 11:44:00"},{"temperature":"19.6","dtg":"2016-07-28 11:43:00"},{"temperature":"19.6","dtg":"2016-07-28 11:42:00"},{"temperature":"19.6","dtg":"2016-07-28 11:41:00"},{"temperature":"19.6","dtg":"2016-07-28 11:40:00"},{"temperature":"19.6","dtg":"2016-07-28 11:39:00"},{"temperature":"19.6","dtg":"2016-07-28 11:38:00"},{"temperature":"19.6","dtg":"2016-07-28 11:37:00"},{"temperature":"19.6","dtg":"2016-07-28 11:36:00"},{"temperature":"19.6","dtg":"2016-07-28 11:35:00"},{"temperature":"19.6","dtg":"2016-07-28 11:34:00"},{"temperature":"19.5","dtg":"2016-07-28 11:33:00"},{"temperature":"19.5","dtg":"2016-07-28 11:32:00"},{"temperature":"19.5","dtg":"2016-07-28 11:31:00"},{"temperature":"19.5","dtg":"2016-07-28 11:30:00"},{"temperature":"19.5","dtg":"2016-07-28 11:29:00"},{"temperature":"19.5","dtg":"2016-07-28 11:28:00"},{"temperature":"19.5","dtg":"2016-07-28 11:27:00"},{"temperature":"19.5","dtg":"2016-07-28 11:26:00"},{"temperature":"19.5","dtg":"2016-07-28 11:25:00"},{"temperature":"19.5","dtg":"2016-07-28 11:24:00"},{"temperature":"19.4","dtg":"2016-07-28 11:23:00"},{"temperature":"19.4","dtg":"2016-07-28 11:22:00"},{"temperature":"19.4","dtg":"2016-07-28 11:21:00"},{"temperature":"19.4","dtg":"2016-07-28 11:20:00"},{"temperature":"19.4","dtg":"2016-07-28 11:19:00"},{"temperature":"19.4","dtg":"2016-07-28 11:18:00"},{"temperature":"19.4","dtg":"2016-07-28 11:17:00"},{"temperature":"19.4","dtg":"2016-07-28 11:16:00"},{"temperature":"19.4","dtg":"2016-07-28 11:15:00"},{"temperature":"19.4","dtg":"2016-07-28 11:14:00"},{"temperature":"19.3","dtg":"2016-07-28 11:13:00"},{"temperature":"19.3","dtg":"2016-07-28 11:12:00"},{"temperature":"19.3","dtg":"2016-07-28 11:11:00"},{"temperature":"19.3","dtg":"2016-07-28 11:10:00"},{"temperature":"19.3","dtg":"2016-07-28 11:09:00"},{"temperature":"19.3","dtg":"2016-07-28 11:08:00"},{"temperature":"19.3","dtg":"2016-07-28 11:07:00"},{"temperature":"19.3","dtg":"2016-07-28 11:06:00"},{"temperature":"19.3","dtg":"2016-07-28 11:05:00"},{"temperature":"19.3","dtg":"2016-07-28 11:04:00"},{"temperature":"19.2","dtg":"2016-07-28 11:03:00"},{"temperature":"19.2","dtg":"2016-07-28 11:02:00"},{"temperature":"19.2","dtg":"2016-07-28 11:01:00"},{"temperature":"19.2","dtg":"2016-07-28 11:00:00"},{"temperature":"19.2","dtg":"2016-07-28 10:59:00"},{"temperature":"19.2","dtg":"2016-07-28 10:58:00"},{"temperature":"19.2","dtg":"2016-07-28 10:57:00"},{"temperature":"19.2","dtg":"2016-07-28 10:56:00"},{"temperature":"19.1","dtg":"2016-07-28 10:55:00"},{"temperature":"19.1","dtg":"2016-07-28 10:54:00"},{"temperature":"19.1","dtg":"2016-07-28 10:53:00"},{"temperature":"19.1","dtg":"2016-07-28 10:52:00"},{"temperature":"19.1","dtg":"2016-07-28 10:51:00"},{"temperature":"19.1","dtg":"2016-07-28 10:50:00"},{"temperature":"19.1","dtg":"2016-07-28 10:49:00"},{"temperature":"19.1","dtg":"2016-07-28 10:48:00"},{"temperature":"19.1","dtg":"2016-07-28 10:47:00"},{"temperature":"19.1","dtg":"2016-07-28 10:46:00"},{"temperature":"19.1","dtg":"2016-07-28 10:45:00"},{"temperature":"19.0","dtg":"2016-07-28 10:44:00"},{"temperature":"19.0","dtg":"2016-07-28 10:43:00"},{"temperature":"19.0","dtg":"2016-07-28 10:42:00"},{"temperature":"19.0","dtg":"2016-07-28 10:41:00"}];

//plot
$(document).ready(function () {
    $.plot($("#placeholder"),  dataset1  );
});

在我的 php 页面内的占位符中显示了一个 float 图形网格，但没有显示任何数据。

如果我使用以下格式将数据硬编码到变量 dataset1 中，则会出现一个图表。

[[1, 300], [2, 600], [3, 550], [4, 400], [5, 300]];

我认为问题可能是由于我对 php 部分中的 json 数据进行了格式化，因此需要对其进行格式化以进行 float 图形绘制。

我很抱歉，因为我是 flot graphs 的新手，并且在我发布这个问题(我的第一个问题)之前尝试了 stackoverflow 中的许多类似解决方案但没有成功。任何帮助将不胜感激!

最佳答案

Flot 期望您的数据集采用与您传入的数据集不同的格式。我通过循环遍历您当前的数据集(您的最后一个示例)以将其置于正确的格式来使其工作。

var dataset1 = [{"temperature":"19.6","dtg":"2016-07-28 12:53:00"},{"temperature":"19.5","dtg":"2016-07-28 12:52:00"},{"temperature":"19.5","dtg":"2016-07-28 12:51:00"},{"temperature":"19.6","dtg":"2016-07-28 12:50:00"},{"temperature":"19.6","dtg":"2016-07-28 12:49:00"},{"temperature":"19.6","dtg":"2016-07-28 12:48:00"},{"temperature":"19.6","dtg":"2016-07-28 12:47:00"},{"temperature":"19.6","dtg":"2016-07-28 12:46:00"},{"temperature":"19.6","dtg":"2016-07-28 12:45:00"},{"temperature":"19.6","dtg":"2016-07-28 12:44:00"},{"temperature":"19.7","dtg":"2016-07-28 12:43:00"},{"temperature":"19.7","dtg":"2016-07-28 12:42:00"},{"temperature":"19.7","dtg":"2016-07-28 12:41:00"},{"temperature":"19.7","dtg":"2016-07-28 12:40:00"},{"temperature":"19.7","dtg":"2016-07-28 12:39:00"},{"temperature":"19.7","dtg":"2016-07-28 12:38:00"},{"temperature":"19.8","dtg":"2016-07-28 12:37:00"},{"temperature":"19.8","dtg":"2016-07-28 12:36:00"},{"temperature":"19.8","dtg":"2016-07-28 12:35:00"},{"temperature":"19.8","dtg":"2016-07-28 12:34:00"},{"temperature":"19.8","dtg":"2016-07-28 12:33:00"},{"temperature":"19.8","dtg":"2016-07-28 12:32:00"},{"temperature":"19.8","dtg":"2016-07-28 12:31:00"},{"temperature":"19.8","dtg":"2016-07-28 12:30:00"},{"temperature":"19.9","dtg":"2016-07-28 12:29:00"},{"temperature":"19.9","dtg":"2016-07-28 12:28:00"},{"temperature":"19.9","dtg":"2016-07-28 12:27:00"},{"temperature":"19.9","dtg":"2016-07-28 12:26:00"},{"temperature":"19.9","dtg":"2016-07-28 12:25:00"},{"temperature":"19.9","dtg":"2016-07-28 12:24:00"},{"temperature":"20.0","dtg":"2016-07-28 12:23:00"},{"temperature":"20.0","dtg":"2016-07-28 12:22:00"},{"temperature":"20.1","dtg":"2016-07-28 12:21:00"},{"temperature":"20.1","dtg":"2016-07-28 12:20:00"},{"temperature":"20.1","dtg":"2016-07-28 12:19:00"},{"temperature":"20.0","dtg":"2016-07-28 12:18:00"},{"temperature":"20.0","dtg":"2016-07-28 12:17:00"},{"temperature":"20.0","dtg":"2016-07-28 12:16:00"},{"temperature":"20.0","dtg":"2016-07-28 12:15:00"},{"temperature":"20.0","dtg":"2016-07-28 12:14:00"},{"temperature":"20.0","dtg":"2016-07-28 12:13:00"},{"temperature":"20.0","dtg":"2016-07-28 12:12:00"},{"temperature":"20.0","dtg":"2016-07-28 12:11:00"},{"temperature":"19.9","dtg":"2016-07-28 12:10:00"},{"temperature":"20.0","dtg":"2016-07-28 12:09:00"},{"temperature":"20.0","dtg":"2016-07-28 12:08:00"},{"temperature":"20.0","dtg":"2016-07-28 12:07:00"},{"temperature":"20.0","dtg":"2016-07-28 12:06:00"},{"temperature":"19.9","dtg":"2016-07-28 12:05:00"},{"temperature":"19.9","dtg":"2016-07-28 12:04:00"},{"temperature":"19.9","dtg":"2016-07-28 12:03:00"},{"temperature":"19.9","dtg":"2016-07-28 12:02:00"},{"temperature":"19.9","dtg":"2016-07-28 12:01:00"},{"temperature":"19.9","dtg":"2016-07-28 12:00:00"},{"temperature":"19.9","dtg":"2016-07-28 11:59:00"},{"temperature":"19.9","dtg":"2016-07-28 11:58:00"},{"temperature":"19.8","dtg":"2016-07-28 11:57:00"},{"temperature":"19.8","dtg":"2016-07-28 11:56:00"},{"temperature":"19.8","dtg":"2016-07-28 11:55:00"},{"temperature":"19.8","dtg":"2016-07-28 11:54:00"},{"temperature":"19.8","dtg":"2016-07-28 11:53:00"},{"temperature":"19.7","dtg":"2016-07-28 11:52:00"},{"temperature":"19.7","dtg":"2016-07-28 11:51:00"},{"temperature":"19.7","dtg":"2016-07-28 11:50:00"},{"temperature":"19.7","dtg":"2016-07-28 11:49:00"},{"temperature":"19.7","dtg":"2016-07-28 11:48:00"},{"temperature":"19.7","dtg":"2016-07-28 11:47:00"},{"temperature":"19.6","dtg":"2016-07-28 11:46:00"},{"temperature":"19.7","dtg":"2016-07-28 11:45:00"},{"temperature":"19.6","dtg":"2016-07-28 11:44:00"},{"temperature":"19.6","dtg":"2016-07-28 11:43:00"},{"temperature":"19.6","dtg":"2016-07-28 11:42:00"},{"temperature":"19.6","dtg":"2016-07-28 11:41:00"},{"temperature":"19.6","dtg":"2016-07-28 11:40:00"},{"temperature":"19.6","dtg":"2016-07-28 11:39:00"},{"temperature":"19.6","dtg":"2016-07-28 11:38:00"},{"temperature":"19.6","dtg":"2016-07-28 11:37:00"},{"temperature":"19.6","dtg":"2016-07-28 11:36:00"},{"temperature":"19.6","dtg":"2016-07-28 11:35:00"},{"temperature":"19.6","dtg":"2016-07-28 11:34:00"},{"temperature":"19.5","dtg":"2016-07-28 11:33:00"},{"temperature":"19.5","dtg":"2016-07-28 11:32:00"},{"temperature":"19.5","dtg":"2016-07-28 11:31:00"},{"temperature":"19.5","dtg":"2016-07-28 11:30:00"},{"temperature":"19.5","dtg":"2016-07-28 11:29:00"},{"temperature":"19.5","dtg":"2016-07-28 11:28:00"},{"temperature":"19.5","dtg":"2016-07-28 11:27:00"},{"temperature":"19.5","dtg":"2016-07-28 11:26:00"},{"temperature":"19.5","dtg":"2016-07-28 11:25:00"},{"temperature":"19.5","dtg":"2016-07-28 11:24:00"},{"temperature":"19.4","dtg":"2016-07-28 11:23:00"},{"temperature":"19.4","dtg":"2016-07-28 11:22:00"},{"temperature":"19.4","dtg":"2016-07-28 11:21:00"},{"temperature":"19.4","dtg":"2016-07-28 11:20:00"},{"temperature":"19.4","dtg":"2016-07-28 11:19:00"},{"temperature":"19.4","dtg":"2016-07-28 11:18:00"},{"temperature":"19.4","dtg":"2016-07-28 11:17:00"},{"temperature":"19.4","dtg":"2016-07-28 11:16:00"},{"temperature":"19.4","dtg":"2016-07-28 11:15:00"},{"temperature":"19.4","dtg":"2016-07-28 11:14:00"},{"temperature":"19.3","dtg":"2016-07-28 11:13:00"},{"temperature":"19.3","dtg":"2016-07-28 11:12:00"},{"temperature":"19.3","dtg":"2016-07-28 11:11:00"},{"temperature":"19.3","dtg":"2016-07-28 11:10:00"},{"temperature":"19.3","dtg":"2016-07-28 11:09:00"},{"temperature":"19.3","dtg":"2016-07-28 11:08:00"},{"temperature":"19.3","dtg":"2016-07-28 11:07:00"},{"temperature":"19.3","dtg":"2016-07-28 11:06:00"},{"temperature":"19.3","dtg":"2016-07-28 11:05:00"},{"temperature":"19.3","dtg":"2016-07-28 11:04:00"},{"temperature":"19.2","dtg":"2016-07-28 11:03:00"},{"temperature":"19.2","dtg":"2016-07-28 11:02:00"},{"temperature":"19.2","dtg":"2016-07-28 11:01:00"},{"temperature":"19.2","dtg":"2016-07-28 11:00:00"},{"temperature":"19.2","dtg":"2016-07-28 10:59:00"},{"temperature":"19.2","dtg":"2016-07-28 10:58:00"},{"temperature":"19.2","dtg":"2016-07-28 10:57:00"},{"temperature":"19.2","dtg":"2016-07-28 10:56:00"},{"temperature":"19.1","dtg":"2016-07-28 10:55:00"},{"temperature":"19.1","dtg":"2016-07-28 10:54:00"},{"temperature":"19.1","dtg":"2016-07-28 10:53:00"},{"temperature":"19.1","dtg":"2016-07-28 10:52:00"},{"temperature":"19.1","dtg":"2016-07-28 10:51:00"},{"temperature":"19.1","dtg":"2016-07-28 10:50:00"},{"temperature":"19.1","dtg":"2016-07-28 10:49:00"},{"temperature":"19.1","dtg":"2016-07-28 10:48:00"},{"temperature":"19.1","dtg":"2016-07-28 10:47:00"},{"temperature":"19.1","dtg":"2016-07-28 10:46:00"},{"temperature":"19.1","dtg":"2016-07-28 10:45:00"},{"temperature":"19.0","dtg":"2016-07-28 10:44:00"},{"temperature":"19.0","dtg":"2016-07-28 10:43:00"},{"temperature":"19.0","dtg":"2016-07-28 10:42:00"},{"temperature":"19.0","dtg":"2016-07-28 10:41:00"}];

var dataset2 = [];
for (var i = 0; i < dataset1.length; i++) {
    dataset2.push( [ Date.parse(dataset1[i].dtg), 
	             parseFloat(dataset1[i].temperature) ] );
}
			
//plot
$(document).ready(function () {
    $.plot( $("#placeholder"),
            [dataset2], // wrap data series in a container
            { xaxis: { mode: "time" } }
    );
});
<script src="https://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js"></script>
<script src="http://cdnjs.cloudflare.com/ajax/libs/flot/0.7/jquery.flot.min.js"></script>
<div id="placeholder" style="width:600px; height:400px; float: left;"></div>

在 var dataset2 = []; 之后，循环解压缩数据集中的每个元素并创建一个 [date, temp] 数据点以添加到数组中。我必须解析日期和 float ，因为 Flot 需要数字数据，而不是字符串。

这将创建一个数据系列。您可以在 Flot 中绘制多个数据系列，因此请注意，我必须在调用 plot 时将该系列包装在另一个容器中。 (换句话说，该容器可能有 [dataset2, dataset3, ..., datasetX]。)

最后一步是在 x 轴上设置 { mode: "time"} 。

关于javascript - 为 flot 图形数组格式化 json 数据，我们在Stack Overflow上找到一个类似的问题： https://stackoverflow.com/questions/38650001/

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