Dynamically update values of a chartjs chart

Mobile Technologies Mobile Computing 2 years ago

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_x000D_ _x000D_ I created an basic bar chart using chartjs and it works fine. Now I want to update the values on a time based interval. My problem is that after I created the chart, I do not know how to update its values correctly... My code: 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 am updating the values with datasets[0].data- is this the right way to do it? The problem with this is that everytime I call chart.Bar(), the values are reset to 0 then animated to the random value (like I am recreating the chart). This way, all animations are always from 0 to value which looks strange. I would expect that if I update a value from 50 to 10 the bar would go down to 10 from 50 and not setted to 0 then animated to 10. I did not found anything in the docs about this... am I doing something wrong or this is impossible with this library?

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manpreet Tuteehub forum best answer Best Answer 2 years ago
_x000D_ Update: Looks like chartjs has been updated (see comment below). There are some examples up that look very nice: Here's an example of updating a line chart using new data: http://jsbin.com/yitep/5/edit Here's how we can update existing data on a line chart: http://jsbin.com/yitep/4/edit Original Post As of Nov 2013, there seem to be very few options for updating charts. There is a good example here (duplicated below) of adding new points to a line chart. Still kind of jumpy but not too bad. However, I think the effect probably depends on the chart you are using. It does look like this is somewhere in the development pipeline. I don't see any indication of a release date yet though: https://github.com/nnnick/Chart.js/issues/13 [Closed as of Jul 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 = { //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 ); }); // ChartJS var Chart=function(s){function v(a,c,b){a=A((a-c.graphMin)/(c.steps*c.stepValue),1,0);return b*c.steps*a}function x(a,c,b,e){function h(){g+=f;var k=a.animation?A(d(g),null,0):1;e.clearRect(0,0,q,u);a.scaleOverlay?(b(k),c()):(c(),b(k));if(1>=g)D(h);else if("function"==typeof a.onAnimationComplete)a.onAnimationComplete()}var f=a.animation?1/A(a.animationSteps,Number.MAX_VALUE,1):1,d=B[a.animationEasing],g=a.animation?0:1;"function"!==typeof c&&(c=function(){});D(h)}function C(a,c,b,e,h,f){var d;a= Math.floor(Math.log(e-h)/Math.LN10);h=Math.floor(h/(1*Math.pow(10,a)))*Math.pow(10,a);e=Math.ceil(e/(1*Math.pow(10,a)))*Math.pow(10,a)-h;a=Math.pow(10,a);for(d=Math.round(e/a);dc;)a=dc?c:!isNaN(parseFloat(b))&& 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