javascript - X 轴的固定比例，从不改变 amcharts

Question

如果你能在X轴上看到 有时间增量6小时 现在，我想将它的刻度更改为 2 小时

昨天刚学这个amchart，不知道怎么用。

这是代码

<script type="text/javascript">
//am4core.useTheme(am4themes_kelly);

am4core.useTheme(am4themes_animated);
// Themes end


// Create chart
var chart = am4core.create("chartdiv", am4charts.XYChart);
chart.paddingRight = 20;

chart.data = generateChartData();

var dateAxis = chart.xAxes.push(new am4charts.DateAxis());
dateAxis.baseInterval = {
  "timeUnit": "minute",
  "count": 1
};
dateAxis.tooltipDateFormat = "HH:mm, d MMMM";

var valueAxis = chart.yAxes.push(new am4charts.ValueAxis());
valueAxis.tooltip.disabled = true;
valueAxis.title.text = "Fin 1";

var series = chart.series.push(new am4charts.LineSeries());
series.dataFields.dateX = "date";
series.dataFields.valueY = "visits";
series.tooltipText = "Stacker: [bold]{valueY}[/]";
series.fillOpacity = 0.3;

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


chart.events.on("datavalidated", function () {
    dateAxis.zoom({start:0, end:1});
});


function generateChartData() {
    var chartData = [];
    // current date
    var firstDate = new Date();
    // now set 12:00 am
    firstDate.setHours(0,0,0,0);

    // and generate 500 data items
    var visits = 0;
    for (var i = 0; i < 1442; i++) {
        var newDate = new Date(firstDate);
        // each time we add one minute
        newDate.setMinutes(newDate.getMinutes() + i);

        chartData.push({
        date: newDate,
        visits: visits
        });

    }
    return chartData;
}
</script>

我已经编辑了代码并可以在这里编辑: https://codepen.io/muhammad-syazani/pen/wLrbQE

Answer 1

是的，使用日期轴可能很棘手。即使您已经使用 amCharts v4 一段时间，也可能不清楚如何按照您想要的方式驯服轴。我强烈推荐阅读 our guide on the Date Axis总而言之，这真的很有帮助。该图表基本上会尝试弄清楚如何将频率很好地放入图表中。

您首先要调整的是 dateAxis.renderer.minGridDistance .默认情况下，它的 120 像素。示例图表有 24 小时，每 2 小时的最小像素间隔为 120px，您的 chart.plotContainer 区域必须为 120 * (24/2)，或至少 1440px，您的浏览器窗口必须比这更宽。因此，如果我们减少它，我们更有可能适应 2 小时间隔网格。

接下来，这是主要成分，是 dateAxis.gridIntervals .如果查看生成的文档，您将看到图表将从中选择的间隔列表。每小时或每 3 小时一次，但不是每 2 小时一次。如果我们用间隔为 2 小时的列表替换该列表，如果它适合，图表将使用它。

您还需要在 scrollBarX 的日期轴上执行相同的操作。

相关代码:

dateAxis.renderer.minGridDistance = 75; // 75 * 24/2 == 900 minimum plotContainer width requisite

var gridIntervals = [
 { timeUnit: "millisecond", count: 1 },
 { timeUnit: "millisecond", count: 5 },
 { timeUnit: "millisecond", count: 10 },
 { timeUnit: "millisecond", count: 50 },
 { timeUnit: "millisecond", count: 100 },
 { timeUnit: "millisecond", count: 500 },
 { timeUnit: "second", count: 1 },
 { timeUnit: "second", count: 5 },
 { timeUnit: "second", count: 10 },
 { timeUnit: "second", count: 30 },
 { timeUnit: "minute", count: 1 },
 { timeUnit: "minute", count: 5 },
 { timeUnit: "minute", count: 10 },
 { timeUnit: "minute", count: 30 },
 { timeUnit: "hour", count: 1 },
 { timeUnit: "hour", count: 2 }, // This is the 2-hour interval
 { timeUnit: "hour", count: 3 },
 { timeUnit: "hour", count: 6 },
 { timeUnit: "hour", count: 12 },
 { timeUnit: "day", count: 1 },
 { timeUnit: "day", count: 2 },
 { timeUnit: "day", count: 3 },
 { timeUnit: "day", count: 4 },
 { timeUnit: "day", count: 5 },
 { timeUnit: "week", count: 1 },
 { timeUnit: "month", count: 1 },
 { timeUnit: "month", count: 2 },
 { timeUnit: "month", count: 3 },
 { timeUnit: "month", count: 6 },
 { timeUnit: "year", count: 1 },
 { timeUnit: "year", count: 2 },
 { timeUnit: "year", count: 5 },
 { timeUnit: "year", count: 10 },
 { timeUnit: "year", count: 50 },
 { timeUnit: "year", count: 100 }
];
dateAxis.gridIntervals.setAll(gridIntervals);

chart.scrollbarX.events.on("validated", function() {
  chart.scrollbarX.scrollbarChart.xAxes.getIndex(0).gridIntervals.setAll(gridIntervals);
});

fork :

https://codepen.io/team/amcharts/pen/9ba62a5bb5239fee149c2d46bf1e4b81

希望这对您有所帮助!

(顺便说一句 - Salaams!我喜欢这个用户名，这是妖精的尾部引用吗？)