Dynamically update chart chart values

Question

I created a basic bar chart using chartjs and it works great. Now I want to update the values ​​in a time interval. My problem is that after creating the chart, I don’t know how to update its values ​​correctly ...

My code is:

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); 

in the test code, I update the values ​​using datasets[0].data - is this the right way to do this? The problem is that every time I call chart.Bar() , the reset values ​​are 0, and then they are animated to a random value (for example, I recreate the chart). Thus, all animations are always from 0 to values ​​that look strange. I would expect that if I update the value from 50 to 10, the bar will decrease to 10 from 50 and will not be set to 0, and then animated to 10.

I did not find anything in the documents ... am I doing something wrong or is it impossible in this library?

Answer 1

Update: it looks like chartjs has been updated (see Comment below). Here are some examples that look very nice:

1. Here is an example of updating a line chart using new data: http://jsbin.com/yitep/5/edit
2. Here's how we can update existing data on a line chart: http://jsbin.com/yitep/4/edit

Original post

As of November 2013, there seem to be very few options for updating the charts.

Here is a good example (duplicated below) of adding new points to a line graph. Still a little nervous, but not too bad. However, I think the effect probably depends on the schedule you are using.

It seems like this is somewhere in the development process. I do not see any indication of the release date yet: https://github.com/nnnick/Chart.js/issues/13 [Closed since July 26, 2014]

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 = { 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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

According to the documentation, there is now an update() method that redraws the chart.

 .update( ) 

Calling update () for your Chart instance will re-render the chart with any updated values, allowing you to edit the value of several existing points and then display them in a single animated rendering cycle.

 myBarChart.datasets[0].bars[2].value = 50; // Would update the first dataset value of 'March' to be 50 myBarChart.update(); // Calling update now animates the position of March from 90 to 50. 

Answer 3

Here's how to do it in the latest version of ChartJs:

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

Take a look at this transparent video.

or test it in jsfiddle

Answer 4

You can also use the destroy () function. Like this

  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

Remove the dom canvas and add again.

 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 6

You just need to change the value of chartObject.data.datasets and call update() as follows:

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

Answer 7

I do not think this is possible now.

However, this feature, which should come soon, as the author hinted here: https://github.com/nnnick/Chart.js/issues/161#issuecomment-20487775

Answer 8

If destroy () and clear () do not work (as I had), you can use jquery to remove the canvas and add it again.

  $('#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 9

I think the easiest way is to write a function to update your chart, including the chart.update() method. Take a look at this simple example that I wrote in jsfiddle for a histogram.

 //value for x-axis var emotions = ["calm", "happy", "angry", "disgust"]; //colours for each bar var colouarray = ['red', 'green', 'yellow', 'blue']; //Let initialData[] be the initial data set var initialData = [0.1, 0.4, 0.3, 0.6]; //Let 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> 

Hope this helps.

Answer 10

The easiest way is to replace the canvas element and call new Chart () again:

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

, yourChartData, yourChartType yourChartOptions , Chart.js. Chart.js .

reloadMyChart . , REST , :

 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 } ); 

Hope it helps!

Answer 11

JS

 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 

,

Answer 12

, .

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