Manipulate Chart Data with Mouse

A line chart you can edit by hand: press anywhere on the plot and drag up or down, and the nearest point follows. Handy for what-if plans and rough forecasts.

  • Try it:
  • Press on the chart and drag up or down
  • Click, then scroll to zoom
Get the code JavaScript JSON
About this chart

When people edit the data

Dragging points turns a chart into an input: people shape a forecast, a budget or a target curve by eye and see the result as they go. The new values are in the chart’s data, ready for your code to save or send on.

Good for

  • What-if planning and rough forecasts
  • Teaching how one change moves a trend
  • Collecting estimates in a survey

Think twice when

  • Exact numbers: offer a table or input boxes too
  • Hundreds of points: each one is too close to the next to pick
  • Data that must not change, like reported results
For developers

Get the code.

Built with amCharts 5, a JavaScript library. The JavaScript includes your theme and renderer (canvas or SVG); the JSON also follows the changes you make with the controls.

Docs:Line seriesValue axisEventsXY chart
// Create root element
// https://www.amcharts.com/docs/v5/getting-started/#Root_element
var root = am5.Root.new("chartdiv");

const myTheme = am5.Theme.new(root); // a theme of our own, for the rule below

myTheme.rule("AxisLabel").setAll({
  fontSize:"0.9em" // axis labels at 90% of the normal text size
});

// Set themes
// https://www.amcharts.com/docs/v5/concepts/themes/
root.setThemes([
  am5themes_Animated.new(root),
  myTheme,
  am5themes_Responsive.new(root)
]);

// Create chart
// https://www.amcharts.com/docs/v5/charts/xy-chart/
var chart = root.container.children.push(am5xy.XYChart.new(root, {
  wheelX: "panX",   // a horizontal wheel or trackpad swipe pans...
  wheelY: "zoomX",  // ...and the vertical wheel zooms in on the dates
  pinchZoomX: true, // pinch with two fingers to zoom on a touch screen
  paddingLeft: 0    // the value labels sit at the chart's left edge
}));

// Add cursor
// https://www.amcharts.com/docs/v5/charts/xy-chart/cursor/
var cursor = chart.set("cursor", am5xy.XYCursor.new(root, {
  behavior: "none" // a drag on the plot neither zooms nor selects, so it can move points
}));
cursor.lineY.set("visible", false); // only the vertical cursor line, no horizontal one

// Generate random data
var date = new Date();
date.setHours(0, 0, 0, 0);
var value = 100;

// one day's point: the value moves randomly by up to 5 from the day before
function generateData() {
  value = Math.round((Math.random() * 10 - 5) + value);
  am5.time.add(date, "day", 1);
  return {
    date: date.getTime(),
    value: value
  };
}

// an array of count daily points
function generateDatas(count) {
  var data = [];
  for (var i = 0; i < count; ++i) {
    data.push(generateData());
  }
  return data;
}

// Create axes
// https://www.amcharts.com/docs/v5/charts/xy-chart/axes/
var xAxis = chart.xAxes.push(am5xy.DateAxis.new(root, {
  maxDeviation: 0.2, // pans up to 20% past the first and last date
  baseInterval: {    // one data point per day
    timeUnit: "day",
    count: 1
  },
  renderer: am5xy.AxisRendererX.new(root, {
    minorGridEnabled: true // fainter grid lines between the labeled ones
  }),
  tooltip: am5.Tooltip.new(root, {}) // a date label follows the cursor along the axis
}));

var yAxis = chart.yAxes.push(am5xy.ValueAxis.new(root, {
  renderer: am5xy.AxisRendererY.new(root, {
    // drag along the value axis labels to zoom it in and out
    pan: "zoom"
  })
}));

// Add series
// https://www.amcharts.com/docs/v5/charts/xy-chart/series/
var series = chart.series.push(am5xy.LineSeries.new(root, {
  name: "Series",
  xAxis: xAxis,
  yAxis: yAxis,
  valueYField: "value",
  valueXField: "date",
  tooltip: am5.Tooltip.new(root, {
    labelText: "{valueY.formatNumber('#.#')}" // the value with up to one decimal
  })
}));

// a hollow dot on each point, with an up-down pointer to hint it can be dragged
series.bullets.push(function() {
  var graphics = am5.Circle.new(root, {
    radius: 4,                    // 4px radius
    interactive: true,            // reacts to the pointer, so the pointer style shows
    cursorOverStyle: "ns-resize", // an up-down arrow pointer over the dot
    stroke: series.get("stroke"), // outlined in the line's color
    // filled with the chart's background color, so the points look hollow in light and dark mode
    fill: root.interfaceColors.get("background")
  });

  return am5.Bullet.new(root, {
    sprite: graphics
  });
});

// Add scrollbar
// https://www.amcharts.com/docs/v5/charts/xy-chart/scrollbars/
chart.set("scrollbarX", am5.Scrollbar.new(root, {
  orientation: "horizontal" // a bar above the plot to zoom and scroll through the dates
}));

// manipulating with mouse code
var isDown = false; // true while the mouse button is held down on the plot

// register down
chart.plotContainer.events.on("pointerdown", function() {
  isDown = true;
})
// register up
chart.plotContainer.events.on("globalpointerup", function() {
  isDown = false;
})

// while the button is held, the point under the cursor follows the pointer up and down
chart.plotContainer.events.on("globalpointermove", function(e) {
  // if pointer is down
  if (isDown) {
    // get tooltip data item
    var tooltipDataItem = series.get("tooltipDataItem");
    if (tooltipDataItem) {
      if (e.originalEvent) {

        // the pointer's height in the plot area, turned into a value on the Y axis
        var position = yAxis.coordinateToPosition(chart.plotContainer.toLocal(e.point).y);
        // rounded to one decimal
        var value = Math.round(yAxis.positionToValue(position) * 10) / 10;
        // need to set both working and original value
        tooltipDataItem.set("valueY", value);
        tooltipDataItem.set("valueYWorking", value);
      }
    }
  }
})

// Set data
var data = generateDatas(40);
series.data.setAll(data);

// Make stuff animate on load
// https://www.amcharts.com/docs/v5/concepts/animations/
series.appear(1000);
chart.appear(1000, 100);

More Line & Area.

All Line & Area demosAll demos
Drawing Chart Series with Mouse or Touch Draggable Range with a Close Button Selecting and Marking Multiple Ranges Line with Custom Bullets