CODEWITHSUNDEEP
javascripthtmld3.js
Andrew
Andrew

Reputation: 21

Dynamically Update Multiple Charts in D3

As stated by the title, I'm trying to dynamically update multiple line charts using D3. I have combined these two examples (http://bl.ocks.org/d3noob/6bd13f974d6516f3e491 and http://bl.ocks.org/d3noob/5987480). Only the first chart is updating with the second remaining static.

Here is the code:

<!DOCTYPE html>
<meta charset="utf-8">
<style> /* set the CSS */

body { font: 12px Arial;}

path { 
stroke: steelblue;
stroke-width: 2;
fill: none;
}

.axis path,
.axis line {
fill: none;
stroke: grey;
stroke-width: 1;
shape-rendering: crispEdges;
}

</style>

<body>

<!-- load the d3.js library --> 
<script src="http://d3js.org/d3.v3.min.js"></script>

<script>

// Set the dimensions of the canvas / graph
var margin = {top: 30, right: 20, bottom: 30, left: 50},
width = 400 - margin.left - margin.right,
height = 220 - margin.top - margin.bottom;

// Parse the date / time
var parseDate = d3.time.format("%H:%M:%S").parse;

// Set the ranges
var x = d3.time.scale().range([0, width]);
var y = d3.scale.linear().range([height, 0]);

// Define the axes
var xAxis = d3.svg.axis().scale(x)
.orient("bottom").ticks(5);

var yAxis = d3.svg.axis().scale(y)
.orient("left").ticks(5);

// Define the line
var valueline = d3.svg.line()
.x(function(d) { return x(d.date); })
.y(function(d) { return y(d.temperature); });

// Adds the svg canvas
var chart1 = d3.select("body")
.append("svg")
    .attr("width", width + margin.left + margin.right)
    .attr("height", height + margin.top + margin.bottom)
.append("g")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

// Get the data
d3.csv("output.csv", function(error, data) {
data.forEach(function(d) {
    d.date = parseDate(d.date);
    d.temperature = +d.temperature;
});

// Scale the range of the data
x.domain(d3.extent(data, function(d) { return d.date; }));
y.domain([0, d3.max(data, function(d) { return d.temperature; })]);

// Add the valueline path.
chart1.append("path")
    .attr("class", "line")
    .attr("d", valueline(data));

// Add the X Axis
chart1.append("g")
    .attr("class", "x axis")
    .attr("transform", "translate(0," + height + ")")
    .call(xAxis);

// Add the Y Axis
chart1.append("g")
    .attr("class", "y axis")
    .call(yAxis);

});

// Adds the svg canvas
var chart2 = d3.select("body")
.append("svg")
    .attr("width", width + margin.left + margin.right)
    .attr("height", height + margin.top + margin.bottom)
.append("g")
    .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

// Get the data
d3.csv("output2.csv", function(error, data) {
data.forEach(function(d) {
    d.date = parseDate(d.date);
    d.humidity = +d.humidity;
});

// Scale the range of the data
x.domain(d3.extent(data, function(d) { return d.date; }));
y.domain([0, d3.max(data, function(d) { return d.humidity; })]);

// Add the valueline path.
chart2.append("path")
    .attr("class", "line")
    .attr("d", valueline(data));

// Add the X Axis
chart2.append("g")
    .attr("class", "x axis")
    .attr("transform", "translate(0," + height + ")")
    .call(xAxis);

// Add the Y Axis
chart2.append("g")
    .attr("class", "y axis")
    .call(yAxis);

});

//2 graph sample code ends here

var TemperatureInterval = setInterval(function() {
            updateTemperatureData();
    }, 5000); 

var HumidityInterval = setInterval(function() {
            updateHumidityData();
    }, 7000); 

function updateTemperatureData() {

// Get the data again
d3.csv("output2.csv", function(error, data) {
    data.forEach(function(d) {
        d.date = parseDate(d.date);
        d.temperature = +d.temperature;
    });

    // Scale the range of the data again 
    x.domain(d3.extent(data, function(d) { return d.date; }));
    y.domain([0, d3.max(data, function(d) { return d.temperature; })]);

// Select the section we want to apply our changes to
var chart1 = d3.select("body").transition();

// Make the changes

    chart1.select(".line")   // change the line
        .duration(750)
        .attr("d", valueline(data));
    chart1.select(".x.axis") // change the x axis
        .duration(750)
        .call(xAxis);
    chart1.select(".y.axis") // change the y axis
        .duration(750)
        .call(yAxis);

});
}

function updateHumidityData() {

// Get the data again
d3.csv("output2.csv", function(error, data) {
    data.forEach(function(d) {
        d.date = parseDate(d.date);
        d.humidity = +d.humidity;
    });

    // Scale the range of the data again 
    x.domain(d3.extent(data, function(d) { return d.date; }));
    y.domain([0, d3.max(data, function(d) { return d.humidity; })]);

// Select the section we want to apply our changes to
var chart2 = d3.select("body").transition();

// Make the changes
    chart2.select(".line")   // change the line
        .duration(750)
        .attr("d", valueline(data));
    chart2.select(".x.axis") // change the x axis
        .duration(750)
        .call(xAxis);
    chart2.select(".y.axis") // change the y axis
        .duration(750)
        .call(yAxis);

});
}

</script>
</body>

Thanks.

Upvotes: 2

Views: 1432

Answers (1)

torresomar
torresomar

Reputation: 2229

Here is a possible approach you can try:

// Adds the svg canvas
var chart1 = d3.select("body")
  .append("svg")
  .attr("class", "chart-1") // Be a little more specific and give a class or identifier to the chart
  .attr("width", width + margin.left + margin.right)
  .attr("height", height + margin.top + margin.bottom)
  .append("g")
  .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

var chart2 = d3.select("body")
  .append("svg")
  .attr("class", "chart-2") // Be a little more specific and give a class or identifier to the chart
  .attr("width", width + margin.left + margin.right)
  .attr("height", height + margin.top + margin.bottom)
  .append("g")
  .attr("transform", "translate(" + margin.left + "," + margin.top + ")");

Add placeholders for the path and axis:

// Chart1 placeholders
chart1.append('path').attr('class', 'line');
chart1.append("g")
  .attr("class", "x axis")
  .attr("transform", "translate(0," + height + ")");
chart1.append("g")
  .attr("class", "y axis");

// Chart2 placeholders
chart2.append('path').attr('class', 'line');
chart2.append("g")
  .attr("class", "x axis")
  .attr("transform", "translate(0," + height + ")");
chart2.append("g")
  .attr("class", "y axis");

Since we don't have a data source we must simulate one:

function fetchData(selector) {
  console.log('fetching');
  return new Promise(function(resolve, reject) {
    // Create new array, each time a different sized one with random values
    var dataLength = Math.floor(Math.random() * 40) + 1;
    var data = [];
    for (var i = 0; i < dataLength; i++) {
      data.push({
        date: randomDate('2016-01-01', '2016-12-01'),
        temperature: Math.floor(Math.random() * 40) + 1
      });
    } 
    setTimeout(function() { // Adding timeout to simulate latency
      // resolve our promise with the newly created data and the selector of the chart we want to update
      resolve({
        data: data,
        selector: selector
      });
    }, 4000)
  })
}

function randomDate() { // helper function
  var startDate = new Date(2012, 0, 1).getTime();
  var endDate = new Date(2015, 0, 1).getTime();
  var spaces = (endDate - startDate);
  var timestamp = Math.round(Math.random() * spaces);
  timestamp += startDate;
  return new Date(timestamp);
}

Then let us create a new function which will update our charts:

function updateChart(resolved) { // receiving the resolved object from our promise 
  var data = resolved.data;
  var selector = resolved.selector;
  data.forEach(function(d) {
    d.date = d.date;
    d.temperature = +d.temperature;
  });
  // sort dates so we don't have issue of line screwing up
  data.sort(function(a, b) {
    return a.date - b.date;
  });
  // Scale the range of the data
  x.domain(d3.extent(data, function(d) {
    return d.date;
  }));
  y.domain([0, d3.max(data, function(d) {
    return d.temperature;
  })]);
  // Since both charts have the same behaviour we can do this
  var selection = d3.select("body").select(selector).transition();
  // Add the valueline path.
  selection.select(".line") // change the line
    .duration(750)
    .attr("d", valueline(data));
  selection.select(".x.axis") // change the x axis
    .duration(750)
    .call(xAxis);
  selection.select(".y.axis") // change the y axis
    .duration(750)
    .call(yAxis);
}

And finally set our update functions:

var HumidityInterval = setInterval(function() {
  fetchData('.chart-1').then(updateChart);
}, 7000);
var TemperatureInterval = setInterval(function() {
  fetchData('.chart-2').then(updateChart);
}, 7000);

Here is a plnkr with the working code if you have any doubts: http://plnkr.co/edit/XlyME4tYlhoW4OgRW1dx?p=preview

Upvotes: 1

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