I am receiving live stocks data from a websocket and pushing the data into an array. I want to plot a line graph with live data.
let aaplArr = new Array(); // creating an empty array
let rowData = x.Data[0].RowData[4]; // this the data received from the websocket
aaplArr.push(rowData); // pushing data into array
let graphPoints = (arr) => {
var myChart = new Chart(ctx, {
type: 'line',
data: {
datasets: [{
data: arr,
backgroundColor: [
'rgba(255, 99, 132, 0.2)',
],
borderColor: [
'rgba(255, 99, 132, 1)',
],
borderWidth: 1
}]
},
});
I want to call the graphPoints(aaplArr) function. I'm not getting the data on the graph. How do I get around this?
I have used HTML canvas for the graph and need to keep reloading the graph for every new value in the array.
You are trying to create the chart again everytime which is inneficient and afaik not even possible, if I am correct chart.js throws an error that the canvas is already in use, to achieve what you want you need to create the chart once outside the function, store in in a variable and then in your graphPoints function you call myChart.data.datasets[0].data.push(...arr) after that you can call the update method on chart.js like so: mychart.update() this will make chart.js update and render all the new values.
I have a donut chart being created by chart.js as follows:
<div id="chartContainer" style="height: 320px; width: 320px">
<canvas id="hoursFEContainer"></canvas>
</div>
I require chart.js as follows (downloaded from npm):-
require('chart.js');
Then in a relevant function I instantiated Chart.js as follows:-
var distinctFeeEarners = ['MEH', 'IHM'];
var totalHoursByFE = [0.8, 0.7];
var chartdata = {
labels: distinctFeeEarners,
datasets : [
{
label: 'Fee Earner',
data: totalHoursByFE
}
]
};
var ctx = $("#hoursFEContainer");
var donutChart = new Chart(ctx, {
type: 'doughnut',
backgroundColor:
['rgba(255, 99, 132, 0.2)',
'rgba(54, 162, 235, 0.2)'],
data: chartdata
});
The chart displays with the correct data, but the donut does not have any colours?
Whats wrong?
EDIT: Beyond stupid, backgroundColor needs to be in datasets not in new Chart. Nevermind.
The reason is that you define backgroundColor at the wrong place. It's a dataset property, hence needs to be defined inside the dataset.
var distinctFeeEarners = ['MEH', 'IHM'];
var totalHoursByFE = [0.8, 0.7];
var chartdata = {
labels: distinctFeeEarners,
datasets: [{
label: 'Fee Earner',
data: totalHoursByFE,
backgroundColor: ['rgba(255, 99, 132, 0.2)', 'rgba(54, 162, 235, 0.2)']
}]
};
var donutChart = new Chart(document.getElementById('hoursFEContainer'), {
type: 'doughnut',
data: chartdata
});
<script src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.9.3/Chart.min.js"></script>
<div id="chartContainer" style="height: 320px; width: 320px">
<canvas id="hoursFEContainer"></canvas>
</div>
Had exactly the same problem with ng2-charts
What did it for me was not pre-initializing dataset.
Prevously i would declare empty array
public data: MultiDataSet = [];
then after backend request resolves i would assign new value
const dataset: Array<number> = new Array();
response.items.map(result => {
dataset.push(result);
});
this.data = [dataset];
This would print doughnut chart but without color. Everything was gray.
Simply not preinitializing MultiDataSet like this fixes things
public data: MultiDataSet; //=[];
I'm currently having a problem which seems to be well known already, but of the answer provided none have worked so far for me.
Whenever I'm hovering over the line in a linegraph, the chart changes back to a chart displayed before as shown in the GIF below:
https://i.stack.imgur.com/cmknf.gif
The solution which seemed the best to me so far is destroying the chart before creating a new one if it's not the first set of data. (bool 'first' and chart 'pauzeAmountChart' are global variables)
function setupAvgPauseGraph(currVideo, currData) {
if (!first) {
pauzeAmountChart.destroy();
}
first = false;
var ctx = document.getElementById("pauzeduurChart");
...
avgPauseChart = new Chart(ctx, {
type: 'line',
data: {
labels: labels,
datasets: [{
label: 'Gemiddelde pauzeduur / seconde',
data: data,
backgroundColor: 'rgba(54, 162, 235, 0.2)',
borderColor: 'rgba(54, 162, 235, 1)',
borderWidth: 1
}]
},
options: {
scales: {
yAxes: [
{ticks: {min: 0, stepSize: step}}],
xAxes: [
{scaleLabel: {display: true, labelString: 'Seconden in video'}}]
},
elements: {point: {radius: 0}}
}
});
}
However, when it's not the first dataset, thus getting to the line 'pauzeAmountChart.destroy()' AND which means the chart already has been initialized and filled with data before, I get this error:
http://prntscr.com/e57x4a
I'm unfortunately not sure what this error means, and Google didn't help me any further either.
Also, when I keep switching between the data the error appears again + 1 more time compared to the previous time the error appeared. Which means it's not actually destroying the graph? (So try #x to show the data gives x errors)
Please let me know if you need any more information.
Thank you in advance!
[EDIT]
Thanks to Guus Punt it's fixed! With a few adjustments, it works now. See below for solution:
function setupPauzeAmountGraph(currVideo, currData) {
var ctx = document.getElementById("aantalPauzesChart");
...
if (pauzeAmountChart != undefined) {
pauzeAmountChart.chart.config.data.labels = labels;
pauzeAmountChart.chart.config.data.datasets[0].data = data;
pauzeAmountChart.update();
} else {
pauzeAmountChart = new Chart(ctx, {
type: 'line',
data: {
labels: labels,
datasets: [{
label: 'Aantal pauzes / seconde',
data: data,
backgroundColor: 'rgba(54, 162, 235, 0.2)',
borderColor: 'rgba(54, 162, 235, 1)',
borderWidth: 1
}]
},
options: {
scales: {
yAxes: [
{ticks: {min: 0, stepSize: step}}],
xAxes: [
{scaleLabel: {display: true, labelString: 'Seconden in video'}}]
},
elements: {point: {radius: 0}}
}
});
}
}
I would need to run your example to be sure but maybe the following would help.
Instead of destroying the chart you can add and remove datasets,
Remove dataset before adding new data
data.labels = []; //Empty label array
data.datasets.splice(0, 1);//Removes first dataset
Add new dataset and labels
Update chart
pauzeAmountChart.update();
I have a working example which retrieves new data from a webapi and updates every 10 seconds, if this isnt sufficient
I've got a question regard Chart.js.
I've drawn multiple piecharts using the documentation provided. I was wondering if on click of a certain slice of one of the charts, I can make an ajax call depending on the value of that slice?
For example, if this is my data
var data = [
{
value: 300,
color:"#F7464A",
highlight: "#FF5A5E",
label: "Red"
},
{
value: 50,
color: "#46BFBD",
highlight: "#5AD3D1",
label: "Green"
},
{
value: 100,
color: "#FDB45C",
highlight: "#FFC870",
label: "Yellow"
}
],
is it possible for me to click on the Red labelled slice and call a url of the following form:
example.com?label=red&value=300? If yes, how do I go about this?
Update: As #Soham Shetty comments, getSegmentsAtEvent(event) only works for 1.x and for 2.x getElementsAtEvent should be used.
.getElementsAtEvent(e)
Looks for the element under the event point, then returns all elements
at the same data index. This is used internally for 'label' mode
highlighting.
Calling getElementsAtEvent(event) on your Chart instance passing an
argument of an event, or jQuery event, will return the point elements
that are at that the same position of that event.
canvas.onclick = function(evt){
var activePoints = myLineChart.getElementsAtEvent(evt);
// => activePoints is an array of points on the canvas that are at the same position as the click event.
};
Example: https://jsfiddle.net/u1szh96g/208/
Original answer (valid for Chart.js 1.x version):
You can achieve this using getSegmentsAtEvent(event)
Calling getSegmentsAtEvent(event) on your Chart instance passing an
argument of an event, or jQuery event, will return the segment
elements that are at that the same position of that event.
From: Prototype Methods
So you can do:
$("#myChart").click(
function(evt){
var activePoints = myNewChart.getSegmentsAtEvent(evt);
/* do something */
}
);
Here is a full working example:
<html>
<head>
<script type="text/javascript" src="http://code.jquery.com/jquery-2.0.2.js"></script>
<script type="text/javascript" src="Chart.js"></script>
<script type="text/javascript">
var data = [
{
value: 300,
color:"#F7464A",
highlight: "#FF5A5E",
label: "Red"
},
{
value: 50,
color: "#46BFBD",
highlight: "#5AD3D1",
label: "Green"
},
{
value: 100,
color: "#FDB45C",
highlight: "#FFC870",
label: "Yellow"
}
];
$(document).ready(
function () {
var ctx = document.getElementById("myChart").getContext("2d");
var myNewChart = new Chart(ctx).Pie(data);
$("#myChart").click(
function(evt){
var activePoints = myNewChart.getSegmentsAtEvent(evt);
var url = "http://example.com/?label=" + activePoints[0].label + "&value=" + activePoints[0].value;
alert(url);
}
);
}
);
</script>
</head>
<body>
<canvas id="myChart" width="400" height="400"></canvas>
</body>
</html>
Using Chart.JS version 2.1.3, answers older than this one aren't valid anymore.
Using getSegmentsAtEvent(event) method will output on console this message:
getSegmentsAtEvent is not a function
So i think it must be removed. I didn't read any changelog to be honest. To resolve that, just use getElementsAtEvent(event) method, as it can be found on the Docs.
Below it can be found the script to obtain effectively clicked slice label and value. Note that also retrieving label and value is slightly different.
var ctx = document.getElementById("chart-area").getContext("2d");
var chart = new Chart(ctx, config);
document.getElementById("chart-area").onclick = function(evt)
{
var activePoints = chart.getElementsAtEvent(evt);
if(activePoints.length > 0)
{
//get the internal index of slice in pie chart
var clickedElementindex = activePoints[0]["_index"];
//get specific label by index
var label = chart.data.labels[clickedElementindex];
//get value by index
var value = chart.data.datasets[0].data[clickedElementindex];
/* other stuff that requires slice's label and value */
}
}
Hope it helps.
Chart.js 2.0 has made this even easier.
You can find it under common chart configuration in the documentation. Should work on more then pie graphs.
options:{
onClick: graphClickEvent
}
function graphClickEvent(event, array){
if(array[0]){
foo.bar;
}
}
It triggers on the entire chart, but if you click on a pie the model of that pie including index which can be used to get the value.
Working fine chartJs sector onclick
ChartJS : pie Chart - Add options "onclick"
options: {
legend: {
display: false
},
'onClick' : function (evt, item) {
console.log ('legend onClick', evt);
console.log('legd item', item);
}
}
I was facing the same issues since several days, Today i have found the solution. I have shown the complete file which is ready to execute.
<html>
<head><script type="text/javascript" src="https://cdnjs.cloudflare.com/ajax/libs/Chart.js/2.7.2/Chart.js">
</script>
</head>
<body>
<canvas id="myChart" width="200" height="200"></canvas>
<script>
var ctx = document.getElementById("myChart").getContext('2d');
var myChart = new Chart(ctx, {
type: 'bar',
data: {
labels: ["Red", "Blue", "Yellow", "Green", "Purple", "Orange"],
datasets: [{
label: '# of Votes',
data: [12, 19, 3, 5, 2, 3],
backgroundColor: [
'rgba(255, 99, 132, 0.2)',
'rgba(54, 162, 235, 0.2)',
'rgba(255, 206, 86, 0.2)',
'rgba(75, 192, 192, 0.2)',
'rgba(153, 102, 255, 0.2)',
'rgba(255, 159, 64, 0.2)'
],
borderColor: [
'rgba(255,99,132,1)',
'rgba(54, 162, 235, 1)',
'rgba(255, 206, 86, 1)',
'rgba(75, 192, 192, 1)',
'rgba(153, 102, 255, 1)',
'rgba(255, 159, 64, 1)'
],
borderWidth: 1
}]
},
options: {
scales: {
yAxes: [{
ticks: {
beginAtZero:true
}
}]
},
onClick:function(e){
var activePoints = myChart.getElementsAtEvent(e);
var selectedIndex = activePoints[0]._index;
alert(this.data.datasets[0].data[selectedIndex]);
}
}
});
</script>
</body>
</html>
If using a Donught Chart, and you want to prevent user to trigger your event on click inside the empty space around your chart circles, you can use the following alternative :
var myDoughnutChart = new Chart(ctx).Doughnut(data);
document.getElementById("myChart").onclick = function(evt){
var activePoints = myDoughnutChart.getSegmentsAtEvent(evt);
/* this is where we check if event has keys which means is not empty space */
if(Object.keys(activePoints).length > 0)
{
var label = activePoints[0]["label"];
var value = activePoints[0]["value"];
var url = "http://example.com/?label=" + label + "&value=" + value
/* process your url ... */
}
};
If you are using TypeScript, the code is a little funky because there is no type inference, but this works to get the index of the data that has been supplied to the chart:
// events
public chartClicked(e:any):void {
//console.log(e);
try {
console.log('DS ' + e.active['0']._datasetIndex);
console.log('ID ' + e.active['0']._index);
console.log('Label: ' + this.doughnutChartLabels[e.active['0']._index]);
console.log('Value: ' + this.doughnutChartData[e.active['0']._index]);
} catch (error) {
console.log("Error In LoadTopGraph", error);
}
try {
console.log(e[0].active);
} catch (error) {
//console.log("Error In LoadTopGraph", error);
}
}
To successfully track click events and on what graph element the user clicked, I did the following in my .js file I set up the following variables:
vm.chartOptions = {
onClick: function(event, array) {
let element = this.getElementAtEvent(event);
if (element.length > 0) {
var series= element[0]._model.datasetLabel;
var label = element[0]._model.label;
var value = this.data.datasets[element[0]._datasetIndex].data[element[0]._index];
}
}
};
vm.graphSeries = ["Series 1", "Serries 2"];
vm.chartLabels = ["07:00", "08:00", "09:00", "10:00"];
vm.chartData = [ [ 20, 30, 25, 15 ], [ 5, 10, 100, 20 ] ];
Then in my .html file I setup the graph as follows:
<canvas id="releaseByHourBar"
class="chart chart-bar"
chart-data="vm.graphData"
chart-labels="vm.graphLabels"
chart-series="vm.graphSeries"
chart-options="vm.chartOptions">
</canvas>
var ctx = document.getElementById('pie-chart').getContext('2d');
var myPieChart = new Chart(ctx, {
// The type of chart we want to create
type: 'pie',
});
//define click event
$("#pie-chart").click(
function (evt) {
var activePoints = myPieChart.getElementsAtEvent(evt);
var labeltag = activePoints[0]._view.label;
});
You can add in the options section an onClick function, like this:
options : {
cutoutPercentage: 50, //for donuts pie
onClick: function(event, chartElements){
if(chartElements){
console.log(chartElements[0].label);
}
},
},
the chartElements[0] is the clicked section of your chart, no need to use getElementsAtEvent anymore.
It works on Chart v2.9.4
I have an elegant solution to this problem. If you have multiple dataset, identifying which dataset was clicked gets tricky. The _datasetIndex always returns zero.
But this should do the trick. It will get you the label and the dataset label as well.
Please note ** this.getElementAtEvent** is without the s in getElement
options: {
onClick: function (e, items) {
var firstPoint = this.getElementAtEvent(e)[0];
if (firstPoint) {
var label = firstPoint._model.label;
var val = firstPoint._model.datasetLabel;
console.log(label+" - "+val);
}
}
}
Within options place your onclick and call the function you need as an example the ajax you need, I'll leave the example so that every click on a point tells you the value and you can use it in your new function.
options: {
plugins: {
// Change options for ALL labels of THIS CHART
datalabels: {
color: 'white',
//backgroundColor:'#ffce00',
align: 'start'
}
},
scales: {
yAxes: [{
ticks: {
beginAtZero:true,
fontColor: "white"
},gridLines: {
color: 'rgba(255,255,255,0.1)',
display: true
}
}],
xAxes: [{
ticks: {
fontColor: "white"
},gridLines: {
display: false
}
}]
},
legend: {
display: false
},
//onClick: abre
onClick:function(e){
var activePoints = myChart.getElementsAtEvent(e);
var selectedIndex = activePoints[0]._index;
alert(this.data.datasets[0].data[selectedIndex]);
}
}