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javascriptchartsamchartsamcharts4

Zooming out remove date but keep time

When I'm zooming in my chart, I can see the date like 26 Apr, 9:05 but when I zoom out I only see time like 9:00. How can I show the date all the time ? Here is my graph (https://codepen.io/anon/pen/GLPPGq) :

am4core.useTheme(am4themes_animated);
var chart = am4core.create("chartdiv", am4charts.XYChart);

chart.dataSource.url = "https://api.myjson.com/bins/i3np8";

chart.dataSource.events.on("parseended", function(ev) {
    var data = ev.target.data;
    data.sort(function(lhs, rhs) {
        return lhs.time - rhs.time;
    });
    data.forEach(function(item) {
        item.time *= 1000;
    });
});

chart.numberFormatter.numberFormat = "#.0b";

chart.dateFormatter.inputDateFormat = "x";
var dateAxis = chart.xAxes.push(new am4charts.DateAxis());

dateAxis.dateFormats.setKey("minute", "d MMM, \nHH:mm");
dateAxis.periodChangeDateFormats.setKey("minute", "d MMM, \nHH:mm");
dateAxis.startLocation = 0.5;
dateAxis.endLocation = 0.5;

var valueAxis = chart.yAxes.push(new am4charts.ValueAxis());
valueAxis.tooltip.disabled = true;

var series = chart.series.push(new am4charts.LineSeries());
series.dataFields.dateX = "time";
series.name = "Traffic out";
series.dataFields.valueY = "outDiffFormatted";
series.tooltipHTML = "<span style='font-size:14px; color:#000000;'><b>{valueY.value}</b></span>";
series.tooltipText = "[#000]{valueY.value}[/]";
series.tooltip.background.fill = am4core.color("#FFF");
series.tooltip.getStrokeFromObject = true;
series.tooltip.background.strokeWidth = 3;
series.tooltip.getFillFromObject = false;
series.fillOpacity = 0.6;
series.strokeWidth = 2;
series.stacked = false;

var series2 = chart.series.push(new am4charts.LineSeries());
series2.dataFields.dateX = "time";
series2.name = "Traffic in";
series2.dataFields.valueY = "inDiffFormatted";
series2.tooltipHTML = "<span style='font-size:14px; color:#000000;'><b>{valueY.value}</b></span>";
series2.tooltipText = "[#000]{valueY.value}[/]";
series2.tooltip.background.fill = am4core.color("#FFF");
series2.tooltip.getFillFromObject = false;
series2.tooltip.getStrokeFromObject = true;
series2.tooltip.background.strokeWidth = 3;
series2.sequencedInterpolation = true;
series2.fillOpacity = 0.5;
series2.stacked = false;
series2.strokeWidth = 2;

chart.cursor = new am4charts.XYCursor();
chart.cursor.lineY.opacity = 0;
chart.cursor.xAxis = dateAxis;
chart.scrollbarX = new am4charts.XYChartScrollbar();
chart.scrollbarX.series.push(series);

chart.legend = new am4charts.Legend();
chart.legend.position = "top";
body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
}

#chartdiv {
    width: 100%;
    height: 500px;
}
    <!DOCTYPE html>
    <html>
        <head>
        <style>

        </style>
        </head>
        <body>
            <script src="https://www.amcharts.com/lib/4/core.js"></script>
            <script src="https://www.amcharts.com/lib/4/charts.js"></script>
            <script src="https://www.amcharts.com/lib/4/themes/animated.js"></script>
            <div id="chartdiv"></div>
        </body>
    </html>

Solution

  • The time change on zoom is due to how AmCharts handles periods - when the time span of visible data reaches a threshold, the chart will upgrade or downgrade the format to a different period's date formatting to ensure the points are more visible. You can change this by modifying the formats in periodChangeDateFormats and dateFormats as described in the dateAxis' formatting date and time documentation like so:

    dateAxis.dateFormats.setKey("hour", "d MMM,\nHH:mm");
dateAxis.periodChangeDateFormats.setKey("hour", "d MMM,\nHH:mm");

    Depending on your data set size, you'll need to set this on multiple periods above and/or below your baseInterval to ensure the desired output for a variety of zoom levels. In your case, add a format to the "hour" key in addition to "minute".

    am4core.useTheme(am4themes_animated);
var chart = am4core.create("chartdiv", am4charts.XYChart);

chart.dataSource.url = "https://api.myjson.com/bins/i3np8";

chart.dataSource.events.on("parseended", function(ev) {
    var data = ev.target.data;
    data.sort(function(lhs, rhs) {
        return lhs.time - rhs.time;
    });
    data.forEach(function(item) {
        item.time *= 1000;
    });
});

chart.numberFormatter.numberFormat = "#.0b";

chart.dateFormatter.inputDateFormat = "x";
var dateAxis = chart.xAxes.push(new am4charts.DateAxis());

dateAxis.dateFormats.setKey("minute", "d MMM, \nHH:mm");
dateAxis.periodChangeDateFormats.setKey("minute", "d MMM, \nHH:mm");
dateAxis.dateFormats.setKey("hour", "d MMM, \nHH:mm");
dateAxis.periodChangeDateFormats.setKey("hour", "d MMM, \nHH:mm");
dateAxis.startLocation = 0.5;
dateAxis.endLocation = 0.5;

var valueAxis = chart.yAxes.push(new am4charts.ValueAxis());
valueAxis.tooltip.disabled = true;

var series = chart.series.push(new am4charts.LineSeries());
series.dataFields.dateX = "time";
series.name = "Traffic out";
series.dataFields.valueY = "outDiffFormatted";
series.tooltipHTML = "<span style='font-size:14px; color:#000000;'><b>{valueY.value}</b></span>";
series.tooltipText = "[#000]{valueY.value}[/]";
series.tooltip.background.fill = am4core.color("#FFF");
series.tooltip.getStrokeFromObject = true;
series.tooltip.background.strokeWidth = 3;
series.tooltip.getFillFromObject = false;
series.fillOpacity = 0.6;
series.strokeWidth = 2;
series.stacked = false;

var series2 = chart.series.push(new am4charts.LineSeries());
series2.dataFields.dateX = "time";
series2.name = "Traffic in";
series2.dataFields.valueY = "inDiffFormatted";
series2.tooltipHTML = "<span style='font-size:14px; color:#000000;'><b>{valueY.value}</b></span>";
series2.tooltipText = "[#000]{valueY.value}[/]";
series2.tooltip.background.fill = am4core.color("#FFF");
series2.tooltip.getFillFromObject = false;
series2.tooltip.getStrokeFromObject = true;
series2.tooltip.background.strokeWidth = 3;
series2.sequencedInterpolation = true;
series2.fillOpacity = 0.5;
series2.stacked = false;
series2.strokeWidth = 2;

chart.cursor = new am4charts.XYCursor();
chart.cursor.lineY.opacity = 0;
chart.cursor.xAxis = dateAxis;
chart.scrollbarX = new am4charts.XYChartScrollbar();
chart.scrollbarX.series.push(series);

chart.legend = new am4charts.Legend();
chart.legend.position = "top";
    body {
    font-family: -apple-system, BlinkMacSystemFont, "Segoe UI", Roboto, Helvetica, Arial, sans-serif, "Apple Color Emoji", "Segoe UI Emoji", "Segoe UI Symbol";
}

#chartdiv {
    width: 100%;
    height: 500px;
}
    <!DOCTYPE html>
    <html>
        <head>
        <style>

        </style>
        </head>
        <body>
            <script src="https://www.amcharts.com/lib/4/core.js"></script>
            <script src="https://www.amcharts.com/lib/4/charts.js"></script>
            <script src="https://www.amcharts.com/lib/4/themes/animated.js"></script>
            <div id="chartdiv"></div>
        </body>
    </html>