Change to a 24 hour format for datetime data in Go

Question

Im plotting data with javascript using the Google Charts API. The default format for datetime data view is the 12 hour am/pm format. How can I change the view to show a 24 hour format? An example of code is shown below, where the default datetime format is used:

var price_data = new google.visualization.DataTable();
         price_data.addColumn('datetime','Time');
         price_data.addColumn('number','Price [øre/KWh]');

price_data.add_row([new Date(2013,23,3,4,5),3])
price_data.add_row([new Date(2013,1,5,4,5),9])

var options = {
      title: 'Price'
    };

var chart = new google.visualization.LineChart(document.getElementById('chart_div'));
chart.draw(data, options);

Answer 1

You can simply pass this in your options,

hAxis: {
        title: 'Time of day',
        format: 'hh:mm a'
    }

    google.charts.load('current', {'packages':['bar']});
    google.charts.setOnLoadCallback(drawChart);

    function drawChart() {

      var data = new google.visualization.DataTable();
      data.addColumn('timeofday', 'Time of Day');
      data.addColumn('number', 'Emails Received');

      data.addRows([
        [[8, 30, 45], 5],
        [[9, 0, 0], 10],
        [[10, 0, 0, 0], 12],
        [[10, 45, 0, 0], 13],
        [[11, 0, 0, 0], 15],
        [[12, 15, 45, 0], 20],
        [[13, 0, 0, 0], 22],
        [[14, 30, 0, 0], 25],
        [[15, 12, 0, 0], 30],
        [[16, 45, 0], 32],
        [[16, 59, 0], 42]
      ]);

      var options = {
        title: 'Total Emails Received Throughout the Day',
        height: 450,
        hAxis: {format:'hh:mm a'}
      };

      var chart = new google.charts.Bar(document.getElementById('chart_div'));

      chart.draw(data, google.charts.Bar.convertOptions(options));
    }

<script type="text/javascript" src="https://www.gstatic.com/charts/loader.js"></script>
   
 <div id="chart_div"></div>

   

Answer 2

You need to format the datetimes using a DateFormatter.

// format dates
// ex: "August 5, 2013 1:45 PM" formatted as "05/08/2013 13:45"
var dateFormatter = new google.visualization.DateFormat({pattern: 'dd/MM/yyyy HH:mm'});
dateFormatter.format(data, 0);

You can format the axis labels by setting the hAxis.format option:

var options = {
    hAxis: {
        format: 'dd/MM/yyyy HH:mm'
    }
    title: 'price'
};

The date formats support most of the ISO date formatting patterns.