javascript - 动态更新chartjs图表的值

Question

我使用 chartjs 创建了一个基本的条形图，它工作正常。现在我想在基于时间的间隔上更新值。我的问题是，创建图表后，我不知道如何正确更新其值...

我的代码：

var ctx = $("#myChart").get(0).getContext("2d");

var dts = [
    {
        fillColor: "rgba(220,220,220,0.5)",
        strokeColor: "rgba(220,220,220,1)",
        data: [0, 0, 0, 0, 0]
    }
];

var data = {
    labels: ["Core#1", "Core#2", "Core#3", "Core#4", "Total"],
    datasets: dts
};

var chart = new Chart(ctx);
chart.Bar(data);

//test code
setInterval( function () {                        
    data.datasets[0].data = [random(), random(), random(), random(), random()];
    chart.Bar(data);

},2000);

在测试代​​码中，我正在更新值datasets[0].data- 这是正确的方法吗？这样做的问题是，每次我调用chart.Bar()时，值都会重置为 0，然后动画为随机值（就像我正在重新创建图表一样）。这样，所有动画总是从 0 到看起来很奇怪的值。我希望如果我将一个值从 50 更新到 10，条形图将从 50 下降到 10，而不是设置为 0，然后动画到 10。

我在文档中没有找到任何关于此的内容......我做错了什么还是这个库不可能？

Answer 1

更新：看起来 chartjs 已经更新（见下面的评论）。上面有一些看起来很不错的例子：

1. 这是使用新数据更新折线图的示例：http: //jsbin.com/yitep/5/edit
2. 以下是我们如何更新折线图上的现有数据：http: //jsbin.com/yitep/4/edit

原帖

截至 2013 年 11 月，更新图表的选项似乎很少。

这里有一个很好的例子（下面重复）向折线图添加新点。仍然有点跳动，但还不错。但是，我认为效果可能取决于您使用的图表。

看起来这确实在开发管道中的某个地方。不过，我还没有看到任何发布日期的迹象：https ://github.com/nnnick/Chart.js/issues/13 [截至 2014 年 7 月 26 日关闭]

JS

$(document).ready(function(){
  var count = 10;
  var data = {
      labels : ["1","2","3","4","5", "6", "7", "8", "9", "10"],
        datasets : [
          {
                fillColor : "rgba(220,220,220,0.5)",
                strokeColor : "rgba(220,220,220,1)",
                pointColor : "rgba(220,220,220,1)",
                pointStrokeColor : "#fff",
                data : [65,59,90,81,56,45,30,20,3,37]
            },
            {
                fillColor : "rgba(151,187,205,0.5)",
                strokeColor : "rgba(151,187,205,1)",
                pointColor : "rgba(151,187,205,1)",
                pointStrokeColor : "#fff",
                data : [28,48,40,19,96,87,66,97,92,85]
            }
        ]
  }
  // this is ugly, don't judge me
  var updateData = function(oldData){
    var labels = oldData["labels"];
    var dataSetA = oldData["datasets"][0]["data"];
    var dataSetB = oldData["datasets"][1]["data"];

    labels.shift();
    count++;
    labels.push(count.toString());
    var newDataA = dataSetA[9] + (20 - Math.floor(Math.random() * (41)));
    var newDataB = dataSetB[9] + (20 - Math.floor(Math.random() * (41)));
    dataSetA.push(newDataA);
    dataSetB.push(newDataB);
    dataSetA.shift();
    dataSetB.shift();    };

  var optionsAnimation = {
    //Boolean - If we want to override with a hard coded scale
    scaleOverride : true,
    //** Required if scaleOverride is true **
    //Number - The number of steps in a hard coded scale
    scaleSteps : 10,
    //Number - The value jump in the hard coded scale
    scaleStepWidth : 10,
    //Number - The scale starting value
    scaleStartValue : 0
  }

  // Not sure why the scaleOverride isn't working...
  var optionsNoAnimation = {
    animation : false,
    //Boolean - If we want to override with a hard coded scale
    scaleOverride : true,
    //** Required if scaleOverride is true **
    //Number - The number of steps in a hard coded scale
    scaleSteps : 20,
    //Number - The value jump in the hard coded scale
    scaleStepWidth : 10,
    //Number - The scale starting value
    scaleStartValue : 0
  }

  //Get the context of the canvas element we want to select
  var ctx = document.getElementById("myChart").getContext("2d");
  var optionsNoAnimation = {animation : false}
  var myNewChart = new Chart(ctx);
  myNewChart.Line(data, optionsAnimation);  

  setInterval(function(){
    updateData(data);
    myNewChart.Line(data, optionsNoAnimation)
    ;}, 2000
  );
});


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(b.lineWidth=c.segmentStrokeWidth,b.strokeStyle=c.segmentStrokeColor,b.stroke());k+=m}},b)},K=function(a,c,b){var e,h,f,d,g,k,j,l,m,t,r,n,p,s=0;g=u;b.font=c.scaleFontStyle+" "+c.scaleFontSize+"px "+c.scaleFontFamily;t=1;for(d=0;d<a.labels.length;d++)e=b.measureText(a.labels[d]).width,t=e>t?e:t;q/a.labels.length<t?(s=45,q/a.labels.length<Math.cos(s)*t?(s=90,g-=t):g-=Math.sin(s)*t):g-=c.scaleFontSize;d=c.scaleFontSize;g=g-5-d;e=Number.MIN_VALUE;h=Number.MAX_VALUE;for(f=0;f<a.datasets.length;f++)for(l=
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for(e=0;e<j.labels.length;e++)h=b.measureText(j.labels[e]).width,d=h>d?h:d;d+=10}r=q-d-t;m=Math.floor(r/(a.labels.length-1));n=q-t/2-r;p=g+c.scaleFontSize/2;x(c,function(){b.lineWidth=c.scaleLineWidth;b.strokeStyle=c.scaleLineColor;b.beginPath();b.moveTo(q-t/2+5,p);b.lineTo(q-t/2-r-5,p);b.stroke();0<s?(b.save(),b.textAlign="right"):b.textAlign="center";b.fillStyle=c.scaleFontColor;for(var d=0;d<a.labels.length;d++)b.save(),0<s?(b.translate(n+d*m,p+c.scaleFontSize),b.rotate(-(s*(Math.PI/180))),b.fillText(a.labels[d],
0,0),b.restore()):b.fillText(a.labels[d],n+d*m,p+c.scaleFontSize+3),b.beginPath(),b.moveTo(n+d*m,p+3),c.scaleShowGridLines&&0<d?(b.lineWidth=c.scaleGridLineWidth,b.strokeStyle=c.scaleGridLineColor,b.lineTo(n+d*m,5)):b.lineTo(n+d*m,p+3),b.stroke();b.lineWidth=c.scaleLineWidth;b.strokeStyle=c.scaleLineColor;b.beginPath();b.moveTo(n,p+5);b.lineTo(n,5);b.stroke();b.textAlign="right";b.textBaseline="middle";for(d=0;d<j.steps;d++)b.beginPath(),b.moveTo(n-3,p-(d+1)*k),c.scaleShowGridLines?(b.lineWidth=c.scaleGridLineWidth,
b.strokeStyle=c.scaleGridLineColor,b.lineTo(n+r+5,p-(d+1)*k)):b.lineTo(n-0.5,p-(d+1)*k),b.stroke(),c.scaleShowLabels&&b.fillText(j.labels[d],n-8,p-(d+1)*k)},function(d){function e(b,c){return p-d*v(a.datasets[b].data[c],j,k)}for(var f=0;f<a.datasets.length;f++){b.strokeStyle=a.datasets[f].strokeColor;b.lineWidth=c.datasetStrokeWidth;b.beginPath();b.moveTo(n,p-d*v(a.datasets[f].data[0],j,k));for(var g=1;g<a.datasets[f].data.length;g++)c.bezierCurve?b.bezierCurveTo(n+m*(g-0.5),e(f,g-1),n+m*(g-0.5),
e(f,g),n+m*g,e(f,g)):b.lineTo(n+m*g,e(f,g));b.stroke();c.datasetFill?(b.lineTo(n+m*(a.datasets[f].data.length-1),p),b.lineTo(n,p),b.closePath(),b.fillStyle=a.datasets[f].fillColor,b.fill()):b.closePath();if(c.pointDot){b.fillStyle=a.datasets[f].pointColor;b.strokeStyle=a.datasets[f].pointStrokeColor;b.lineWidth=c.pointDotStrokeWidth;for(g=0;g<a.datasets[f].data.length;g++)b.beginPath(),b.arc(n+m*g,p-d*v(a.datasets[f].data[g],j,k),c.pointDotRadius,0,2*Math.PI,!0),b.fill(),b.stroke()}}},b)},L=function(a,
c,b){var e,h,f,d,g,k,j,l,m,t,r,n,p,s,w=0;g=u;b.font=c.scaleFontStyle+" "+c.scaleFontSize+"px "+c.scaleFontFamily;t=1;for(d=0;d<a.labels.length;d++)e=b.measureText(a.labels[d]).width,t=e>t?e:t;q/a.labels.length<t?(w=45,q/a.labels.length<Math.cos(w)*t?(w=90,g-=t):g-=Math.sin(w)*t):g-=c.scaleFontSize;d=c.scaleFontSize;g=g-5-d;e=Number.MIN_VALUE;h=Number.MAX_VALUE;for(f=0;f<a.datasets.length;f++)for(l=0;l<a.datasets[f].data.length;l++)a.datasets[f].data[l]>e&&(e=a.datasets[f].data[l]),a.datasets[f].data[l]<
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Math.floor(r/a.labels.length);s=(m-2*c.scaleGridLineWidth-2*c.barValueSpacing-(c.barDatasetSpacing*a.datasets.length-1)-(c.barStrokeWidth/2*a.datasets.length-1))/a.datasets.length;n=q-t/2-r;p=g+c.scaleFontSize/2;x(c,function(){b.lineWidth=c.scaleLineWidth;b.strokeStyle=c.scaleLineColor;b.beginPath();b.moveTo(q-t/2+5,p);b.lineTo(q-t/2-r-5,p);b.stroke();0<w?(b.save(),b.textAlign="right"):b.textAlign="center";b.fillStyle=c.scaleFontColor;for(var d=0;d<a.labels.length;d++)b.save(),0<w?(b.translate(n+
d*m,p+c.scaleFontSize),b.rotate(-(w*(Math.PI/180))),b.fillText(a.labels[d],0,0),b.restore()):b.fillText(a.labels[d],n+d*m+m/2,p+c.scaleFontSize+3),b.beginPath(),b.moveTo(n+(d+1)*m,p+3),b.lineWidth=c.scaleGridLineWidth,b.strokeStyle=c.scaleGridLineColor,b.lineTo(n+(d+1)*m,5),b.stroke();b.lineWidth=c.scaleLineWidth;b.strokeStyle=c.scaleLineColor;b.beginPath();b.moveTo(n,p+5);b.lineTo(n,5);b.stroke();b.textAlign="right";b.textBaseline="middle";for(d=0;d<j.steps;d++)b.beginPath(),b.moveTo(n-3,p-(d+1)*
k),c.scaleShowGridLines?(b.lineWidth=c.scaleGridLineWidth,b.strokeStyle=c.scaleGridLineColor,b.lineTo(n+r+5,p-(d+1)*k)):b.lineTo(n-0.5,p-(d+1)*k),b.stroke(),c.scaleShowLabels&&b.fillText(j.labels[d],n-8,p-(d+1)*k)},function(d){b.lineWidth=c.barStrokeWidth;for(var e=0;e<a.datasets.length;e++){b.fillStyle=a.datasets[e].fillColor;b.strokeStyle=a.datasets[e].strokeColor;for(var f=0;f<a.datasets[e].data.length;f++){var g=n+c.barValueSpacing+m*f+s*e+c.barDatasetSpacing*e+c.barStrokeWidth*e;b.beginPath();
b.moveTo(g,p);b.lineTo(g,p-d*v(a.datasets[e].data[f],j,k)+c.barStrokeWidth/2);b.lineTo(g+s,p-d*v(a.datasets[e].data[f],j,k)+c.barStrokeWidth/2);b.lineTo(g+s,p);c.barShowStroke&&b.stroke();b.closePath();b.fill()}}},b)},D=window.requestAnimationFrame||window.webkitRequestAnimationFrame||window.mozRequestAnimationFrame||window.oRequestAnimationFrame||window.msRequestAnimationFrame||function(a){window.setTimeout(a,1E3/60)},F={}};

HTML

<html>
    <head>
        <script src="//ajax.googleapis.com/ajax/libs/jquery/1.9.1/jquery.min.js"></script>
    </head>
    <body>
        <h1>Live Updating Chart.js</h1>

        <canvas id="myChart" width="400" height="150"></canvas>


    </body>
</html>

Answer 2

触发图表的update()更新。图表更新（）

.update(config)

触发图表的更新。这可以在更新数据对象后安全地调用。这将更新所有比例、图例，然后重新渲染图表。可以config为对象提供更新过程的附加配置。

update()可以在更新数据对象中的一个或多个现有点的值后安全地调用，在一个动画渲染循环中渲染更改。

// update the first dataset's value of 'March' to be 50
myBarChart.data.datasets[0].bars[2].value = 50;

// animate update of 'March' from 90 to 50.
myBarChart.update();

Answer 3

以下是在 ChartJs 的最新版本中执行此操作的方法：

setInterval(function(){
    chart.data.datasets[0].data[5] = 80;
    chart.data.labels[5] = "Newly Added";
    chart.update();
}

看这个清晰的视频

或者在jsfiddle中测试它

Answer 4

您也可以使用 destroy() 函数。像这样

 if( window.myBar!==undefined)
     window.myBar.destroy();
 var ctx = document.getElementById("canvas").getContext("2d");
 window.myBar = new Chart(ctx).Bar(barChartData, {
     responsive : true,
 });

Answer 5

您只需要更改chartObject.data.datasets值并update()像这样调用：

chartObject.data.datasets = newData.datasets;
chartObject.data.labels = newData.labels;
chartObject.update();

Answer 6

移除画布 dom 并再次添加。

function renderChart(label,data){

    $("#canvas-wrapper").html("").html('<canvas id="storeSends"></canvas>');
    var lineChartData = {
        labels : label,
        datasets : [
            {
                fillColor : "rgba(49, 195, 166, 0.2)",
                strokeColor : "rgba(49, 195, 166, 1)",
                pointColor : "rgba(49, 195, 166, 1)",
                pointStrokeColor : "#fff",
                data : data
            }
        ]

    }
    var canvas = document.getElementById("storeSends");
    var ctx = canvas.getContext("2d");

    myLine = new Chart(ctx).Line(lineChartData, {
        responsive: true,
        maintainAspectRatio: false
    });
}

Answer 7

如果 destroy() 和 clear() 不起作用（就像我的经验一样），您可以使用 jquery 删除画布并再次附加它。

    $('#chartAmazon').remove();
    $('#chartBar').append('<canvas id="chartAmazon"></canvas>');

    var ctxAmazon = $("#chartAmazon").get(0).getContext("2d");
      var AmazonChart = new Chart(ctxAmazon, {
        type: 'doughnut',
        data: dataAmazon,
        options: optionsA
    });

Answer 8

我认为最简单的方法是编写一个函数来更新您的图表，包括该chart.update()方法。查看我在 jsfiddle 中为条形图编写的这个简单示例。

//value for x-axis
var emotions = ["calm", "happy", "angry", "disgust"];

//colours for each bar
var colouarray = ['red', 'green', 'yellow', 'blue'];

//Let's initialData[] be the initial data set
var initialData = [0.1, 0.4, 0.3, 0.6];

//Let's updatedDataSet[] be the array to hold the upadted data set with every update call
var updatedDataSet;

/*Creating the bar chart*/
var ctx = document.getElementById("barChart");
var barChart = new Chart(ctx, {
  type: 'bar',
  data: {
    labels: emotions,
    datasets: [{
      backgroundColor: colouarray,
      label: 'Prediction',
      data: initialData
    }]
  },
  options: {
    scales: {
      yAxes: [{
        ticks: {
          beginAtZero: true,
          min: 0,
          max: 1,
          stepSize: 0.5,
        }
      }]
    }
  }
});

/*Function to update the bar chart*/
function updateBarGraph(chart, label, color, data) {
  chart.data.datasets.pop();
  chart.data.datasets.push({
    label: label,
    backgroundColor: color,
    data: data
  });
  chart.update();
}

/*Updating the bar chart with updated data in every second. */
setInterval(function() {
  updatedDataSet = [Math.random(), Math.random(), Math.random(), Math.random()];
  updateBarGraph(barChart, 'Prediction', colouarray, updatedDataSet);
}, 1000);

<html>

<head>
  <script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.3.0/Chart.min.js"></script>

<body>
    <div>
      <h1>Update Bar Chart</h1>
      <canvas id="barChart" width="800" height="450"></canvas>
    </div>
    <script src="barchart.js"></script>
  </body>
  
</head>

</html>

希望这可以帮助。

Answer 9

我认为现在不可能。

然而，正如作者在这里暗示的那样，这是一个很快就会出现的功能： https ://github.com/nnnick/Chart.js/issues/161#issuecomment-20487775

Answer 10

有2种方法可以解决：

1. chart.update()

2. 使用 chart.destroy() 删除现有图表并创建新图表对象。

Answer 11

这是ChartJs 的示例 - 2.9.4

var maximumPoints = 5;// with this variable you can decide how many points are display on the chart
        function addData(chart, label, data) {
            chart.data.labels.push(label);
            chart.data.datasets.forEach((dataset) => {
                var d = data[0];
                dataset.data.push(d);
                data.shift();
            });


            var canRemoveData = false;
            chart.data.datasets.forEach((dataset) => {
                if (dataset.data.length > maximumPoints) {

                    if (!canRemoveData) {
                        canRemoveData = true;
                        chart.data.labels.shift();
                    }

                    dataset.data.shift();

                }

            });



            chart.update();
        }




        window.onload = function () {
            var canvas = document.getElementById('elm-chart'),
                ctx = canvas.getContext('2d');

            var myLineChart = new Chart(ctx, {
                type: 'line',
                data: {
                    labels: [],
                    datasets: [
                        {
                            data: [],
                            label: 'Dataset-1',
                            backgroundColor: "#36a2eb88",
                            borderColor: "#36a2eb",
                        },
                        {
                            data: [],
                            label: 'Dataset-2',
                            backgroundColor: "#ff638488",
                            borderColor: "#ff6384",
                        }
                    ],

                },
                options: {
                    responsive: false,
                    maintainAspectRatio: false,
                    scales: {
                        yAxes: [{
                            ticks: {
                                beginAtZero: true
                            }
                        }]
                    }
                }
            });

            var index = 0;
            setInterval(function () {

                var data = [];
                myLineChart.data.datasets.forEach((dataset) => {
                    data.push(Math.random() * 100);
                });

                addData(myLineChart, index, data);
                index++;

            }, 1000);
        }

<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.9.4/Chart.min.js"></script>
<canvas id="elm-chart" width="640" height="480"></canvas>

Answer 12

最简单的方法是替换 canvas 元素，然后再次调用 new Chart()：

function reloadMyChart() {
    $('myChart').replaceWith('<canvas id="myChart"></canvas>');
    new Chart(document.getElementById("myChart"), {
        data: yourChartData,
        type: yourChartType,
        options: yourChartOptions
    });
}

当然，您必须将 yourChartData、yourChartType 和 yourChartOptions 替换为初始化 Chart.js 所需的正确值。请参阅Chart.js 文档。

您可以在按钮单击或您需要的任何其他事件上调用 reloadMyChart 函数。您可能会向该函数添加参数并使用这些参数进行 REST 调用以动态更新图表，如下所示：

function reloadMyChart(param1, param2) {
    $('myChart').replaceWith('<canvas id="myChart"></canvas>');
    $.get("restUrl?param1=" + param1 + "&param2=" + param2 + ",
        function(data) {
            // call new Chart() here and use returned data
        }
    );

希望能帮助到你！=)

Answer 13

显示实时更新chartJS

function add_data(chart, label, data) 
      {
        var today = new Date();
        var time = today.getHours() + ":" + today.getMinutes() + ":" + today.getSeconds();
        myLineChart.data.datasets[0].data.push(Math.random() * 100);
        myLineChart.data.datasets[1].data.push(Math.random() * 100);
        myLineChart.data.labels.push(time)
        myLineChart.update();
      }
      setInterval(add_data, 10000); //milisecond

完整代码，您可以在描述链接中下载

Answer 14

您可以Chart使用Chart.instances. 这将为您提供所有图表实例。现在您可以迭代该实例并更改配置中存在的数据。假设您的页面中只有一个图表。

for (var _chartjsindex in Chart.instances) {
/* 
 * Here in the config your actual data and options which you have given at the 
   time of creating chart so no need for changing option only you can change data
*/
 Chart.instances[_chartjsindex].config.data = [];
 // here you can give add your data
 Chart.instances[_chartjsindex].update();
 // update will rewrite your whole chart with new value
 }

Answer 15

如此简单，只需替换图表画布元素即可。

$('#canvas').replaceWith('id="canvas" height="200px" width="368px">');