Time data with irregular intervals

author(s): Torstein Hønsi

HTML

<script src="https://code.highcharts.com/highcharts.js"></script>
<script src="https://code.highcharts.com/modules/series-label.js"></script>
<script src="https://code.highcharts.com/modules/exporting.js"></script>
<script src="https://code.highcharts.com/modules/export-data.js"></script>
<script src="https://code.highcharts.com/modules/accessibility.js"></script>

<figure class="highcharts-figure">
    <div id="container"></div>
    <p class="highcharts-description">
        This demo visualizes a data set with irregular time intervals.
        Highcharts comes with sophisticated functionality for dealing
        with time data, including support for different time zones and
        irregular intervals.
    </p>
</figure>

CSS

body {
    font-family:
        -apple-system,
        BlinkMacSystemFont,
        "Segoe UI",
        Roboto,
        Helvetica,
        Arial,
        "Apple Color Emoji",
        "Segoe UI Emoji",
        "Segoe UI Symbol",
        sans-serif;
    background: var(--highcharts-background-color);
    color: var(--highcharts-neutral-color-100);
}

.highcharts-figure,
.highcharts-data-table table {
    min-width: 310px;
    max-width: 800px;
    margin: 1em auto;
}

.highcharts-data-table table {
    font-family: Verdana, sans-serif;
    border-collapse: collapse;
    border: 1px solid var(--highcharts-neutral-color-10, #e6e6e6);
    margin: 10px auto;
    text-align: center;
    width: 100%;
    max-width: 500px;
}

.highcharts-data-table caption {
    padding: 1em 0;
    font-size: 1.2em;
    color: var(--highcharts-neutral-color-60, #666);
}

.highcharts-data-table th {
    font-weight: 600;
    padding: 0.5em;
}

.highcharts-data-table td,
.highcharts-data-table th,
.highcharts-data-table caption {
    padding: 0.5em;
}

.highcharts-data-table thead tr,
.highcharts-data-table tbody tr:nth-child(even) {
    background: var(--highcharts-neutral-color-3, #f7f7f7);
}

.highcharts-description {
    background: light-dark(#f2f6f2, #323232);
    border-radius: 0 4px 4px 0;
    border-left: 2px solid light-dark(#1d6aff, #fff);
    font-size: 0.8rem;
    font-style: italic;
    padding: 8px 16px;
    margin: 2em 10px 1em;
}

JavaScript

// Data retrieved from https://www.vikjavev.no/ver/snjomengd

Highcharts.chart('container', {
    chart: {
        type: 'spline'
    },
    title: {
        text: 'Snow depth at Vikjafjellet, Norway'
    },
    subtitle: {
        text: 'Irregular time data in Highcharts JS'
    },
    xAxis: {
        type: 'datetime',
        dateTimeLabelFormats: {
            // don't display the year
            month: '%e. %b',
            year: '%b'
        },
        title: {
            text: 'Date'
        }
    },
    yAxis: {
        title: {
            text: 'Snow depth (m)'
        },
        min: 0
    },
    tooltip: {
        headerFormat: '<b>{series.name}</b><br>',
        pointFormat: '{point.x:%e. %b}: {point.y:.2f} m'
    },

    plotOptions: {
        series: {
            marker: {
                symbol: 'circle',
                fillColor: 'var(--highcharts-background-color, #ffffff)',
                enabled: true,
                radius: 2.5,
                lineWidth: 1,
                lineColor: null
            }
        }
    },

    colors: ['#6CF', '#39F', '#06C', '#036', '#000'],

    // Define the data points. All series have a year of 1970/71 in order
    // to be compared on the same x axis.
    series: [
        {
            name: 'Winter 2021-2022',
            data: [
                ['1970-11-05', 0],
                ['1970-11-12', 0.1],
                ['1970-11-21', 0.15],
                ['1970-11-22', 0.19],
                ['1970-11-27', 0.17],
                ['1970-11-30', 0.27],
                ['1970-12-02', 0.25],
                ['1970-12-04', 0.27],
                ['1970-12-05', 0.26],
                ['1970-12-06', 0.25],
                ['1970-12-07', 0.26],
                ['1970-12-08', 0.26],
                ['1970-12-09', 0.25],
                ['1970-12-10', 0.25],
                ['1970-12-11', 0.25],
                ['1970-12-12', 0.26],
                ['1970-12-22', 0.22],
                ['1970-12-23', 0.22],
...