Combining two arrays and send them to Highcharts

I am trying to adapt the code obtained on the web for my use. I have a lot of experience in C, C++ and Python, but almost none in PHP, so I do not know where to start, because I don’t fully understand code and PHP concepts.

So the idea is that the program reads data from the SQL table, etime is epoch time (integer) and value are float values (strings). Then those data are plotted using Highcharts, where in the original code etime is category.

PHP part:

$etime = json_encode(array_reverse(array_column($sensor_data, 'etime')), JSON_NUMERIC_CHECK);
$value = json_encode(array_reverse(array_column($sensor_data, 'value')), JSON_NUMERIC_CHECK);

var etime = <?php echo $etime; ?>;
var value = <?php echo $value; ?>;

Javascript (?) part:

var chartT = new Highcharts.Chart({
  series: [{
    data: value
  }],
  xAxis: { 
    categories: etime
  }
});

I would like to adapt this code so that etime is datetime instead of category. As far as I understand from the web, I should combine arrays $etime and $value into an array of pairs [$etime, $value] and change categories: etime to type: 'datetime'. However, I do not know how to do that.

As an example $etime = [0,1,2] and $value = [3,4,5], and I need [[0,3],[1,4],[2,5]].

Can you please help me with this?

>Solution :

The PHP can combine the data content like this.
You need to multiply the time by 1000 to get the MS that JS/HighChart expects

// Assuming $sensor_data is already populated with your data
$combined_data = array();
foreach ($sensor_data as $data) {
    $etime_millisec = intval($data['etime']) * 1000; // Convert to milliseconds
    $value = floatval($data['value']); // Ensure value is a float
    $combined_data[] = array($etime_millisec, $value);
}

$combined_data_json = json_encode(array_reverse($combined_data), JSON_NUMERIC_CHECK);

Then in the HighChart part you can change to datetime

var chartData = <?php echo $combined_data_json; ?>;

var chartT = new Highcharts.Chart({
    series: [{
        data: chartData
    }],
    xAxis: { 
        type: 'datetime' // Changed from 'categories' to 'datetime'
    }
});