跳过克：负采样部分

Question

我正在使用负采样方法从头开始实现一个跳过语法模型。我自己完成了一些工作，然后在互联网上搜索了一些其他部分的帮助。

在某些时候，我必须建立所有频率加上频率之和。但是，为了构建负采样，我发现了一些我不理解的代码。您能告诉我这段代码的目的是什么？

let chart = am4core.create("chartdiv", am4charts.XYChart);
chart.data = [{
  tran_amount: 125.0,
  value_date: new Date("2019-01-05T12:00:00.000")
}, {
  tran_amount: 12345.0,
  value_date: new Date("2019-02-05T12:00:00.000")
}, {
  tran_amount: 12345.0,
  value_date: new Date("2019-03-05T12:00:00.000")
}];
let categoryAxis = chart.xAxes.push(new am4charts.DateAxis());
categoryAxis.start = 0.7;
categoryAxis.keepSelection = true;
let valueAxis = chart.yAxes.push(new am4charts.ValueAxis());
let lineSeries = chart.series.push(new am4charts.LineSeries());
lineSeries.dataFields.valueY = "tran_amount";
lineSeries.dataFields.dateX = "value_date";
chart.cursor = new am4charts.XYCursor();
chart.cursor.behavior = 'panX';
chart.scrollbarX = new am4core.Scrollbar();
chart.zoomOutButton.disabled = true;
chart.swipeable = true;