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intro_d3js.html
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intro_d3js.html
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<!DOCTYPE html>
<html lang="en">
<head>
<!-- AdThrive Head Tag Manual -->
<script data-no-optimize="1" data-cfasync="false">
(function (w, d) {
w.adthrive = w.adthrive || {};
w.adthrive.cmd = w.adthrive.cmd || [];
w.adthrive.plugin = "adthrive-ads-manual";
w.adthrive.host = "ads.adthrive.com";
var s = d.createElement("script");
s.async = true;
s.referrerpolicy = "no-referrer-when-downgrade";
s.src =
"https://" +
w.adthrive.host +
"/sites/643436a4e6d20859e40a446b/ads.min.js?referrer=" +
w.encodeURIComponent(w.location.href) +
"&cb=" +
(Math.floor(Math.random() * 100) + 1);
var n = d.getElementsByTagName("script")[0];
n.parentNode.insertBefore(s, n);
})(window, document);
</script>
<!-- End of AdThrive Head Tag -->
<!-- Global site tag (gtag.js) - Google Analytics -->
<script
async
src="https://www.googletagmanager.com/gtag/js?id=UA-79254642-6"
></script>
<script>
window.dataLayer = window.dataLayer || [];
function gtag() {
dataLayer.push(arguments);
}
gtag("js", new Date());
gtag("config", "UA-79254642-6");
</script>
<script>
var getOutboundLink = function (url) {
gtag("event", "click", {
event_category: "outbound",
event_label: url,
transport_type: "beacon",
event_callback: function () {
document.location = url;
},
});
};
</script>
<meta charset="utf-8" />
<title>An introduction to d3.js in 10 basic examples</title>
<meta
name="viewport"
content="width=device-width, initial-scale=1, shrink-to-fit=no"
/>
<meta
name="description"
content="A set of 10 basic examples leading to a first chart made with d3.js. Discover the basics: html, css, svg, scale, data binding and more. Explanation and editable code provided"
/>
<meta
name="keywords"
content="Data,Dataviz,Datavisualization,Javascript, JS, d3.js, axis, x, y"
/>
<meta name="author" content="Yan Holtz" />
<link rel="icon" href="img/logo/D3_single_small.png" />
<meta
property="og:title"
content="An introduction to d3.js in 10 basic examples."
/>
<meta property="og:image" content="img/overview_RGG.png" />
<meta
property="og:description"
content="A set of 10 basic examples leading to a first chart made with d3.js. Discover the basics: html, css, svg, scale, data binding and more. Explanation and editable code provided."
/>
<!-- Bootstrap core CSS -->
<link href="vendor/bootstrap/css/bootstrap.min.css" rel="stylesheet" />
<!-- Custom fonts for this template -->
<link
href="vendor/font-awesome/css/font-awesome.min.css"
rel="stylesheet"
type="text/css"
/>
<!-- Custom styles for this template -->
<link href="css/agency.css" rel="stylesheet" />
<!-- PRISM -->
<script src="LIB/prism.js"></script>
<link href="LIB/prism.css" rel="stylesheet" />
<!-- D3.JS v4 -->
<script src="js/d3.v4.js"></script>
<!-- JQUERY -->
<script src="vendor/jquery/jquery.min.js"></script>
<!-- HTML TO CANVAS -->
<script src="js/html2canvas.js"></script>
<!-- Function to parse html and js code chunks made by Yan Holtz -->
<script src="js/myParser.js"></script>
<!-- Bootstrap js -->
<script src="vendor/bootstrap/js/bootstrap.bundle.min.js"></script>
<script src="js/agency.min.js"></script>
</head>
<body data-spy="scroll" data-target="#myScrollspy" data-offset="1">
<!-- THIS ALLOWS TO INSERT THE MENU THAT IS STORED IN A MENU.HTML FILE-->
<nav class="navbar navbar-expand-lg fixed-top" id="mainNav"></nav>
<script>
$(function () {
$("#mainNav").load("html_chunk/menu.html");
});
</script>
<!-- THIS ALLOWS TO INSERT THE MODAL OF THE MENU THAT IS STORED IN A MENU_MODAL.HTML FILE-->
<div id="modal_menu_insertion"></div>
<script>
$(function () {
$("#modal_menu_insertion").load("html_chunk/menu_modal.html");
});
</script>
<!-- Header -->
<header class="masthead" style="padding-top: 150px; padding-bottom: 80px">
<div class="textlanding">
<h1>An introduction to d3.js in 10 basic examples.</h1>
<hr class="short_hr" />
<br />
<ul class="list-inline social-buttons">
<li class="list-inline-item">
<a href="https://twitter.com/R_Graph_Gallery">
<i class="fa fa-twitter"></i>
</a>
</li>
<li class="list-inline-item social-buttons">
<a href="https://github.com/holtzy">
<i class="fa fa-github" style="color: white"></i>
</a>
</li>
<li class="list-inline-item social-buttons">
<a href="https://www.linkedin.com/in/yan-holtz-2477534a/">
<i class="fa fa-linkedin"></i>
</a>
</li>
</ul>
<br /><br />
<p style="max-width: 700px; margin: auto">
<a href="https://d3js.org">D3.js</a> is a
<u>JavaScript library</u> for manipulating documents based on data. It
allows to build absolutely
<a href="all.html">any type of data visualization</a>. This document
displays 10 interactive examples illustrating the key concepts of d3,
leading to a first basic scatterplot. Note that this
<a
href="https://click.linksynergy.com/deeplink?id=G7VKNifkCIY&mid=39197&murl=https%3A%2F%2Fwww.udemy.com%2Fcourse%2Flearn-d3js-for-data-visualization%2F"
>online course</a
>
is a great resource to get you started with d3.js.
</p>
</div>
</header>
<!-- TABLE of CONTENT -->
<div>
<nav class="col-sm-3 col-4" id="myScrollspy">
<ul class="nav nav-pills flex-column">
<li class="nav-item">
<a class="nav-link active" href="#html">HTML</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#css">CSS</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#svg">SVG</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#d3">Javascript and d3.js</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#log">Console.log()</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#coord">Coordinate system</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#scale">Scale</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#axis">Axis</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#margin">Margin</a>
</li>
<li class="nav-item">
<a class="nav-link" href="#data">Data binding</a>
</li>
</ul>
</nav>
</div>
<!-- ==================== HTML ==================== -->
<section id="html">
<div class="container">
<h1>What is <code>HTML</code>?</h1>
<hr />
<code>→ Explanation:</code>
<br />
<ul style="margin-top: 5px">
<li>
<a href="https://en.wikipedia.org/wiki/HTML">HTML</a> stands for
<u>Hypertext Markup Language</u>. Basically, it is the language
behind any <u>website</u>. Web browsers like Mozilla or Safari read
this kind of file and translate it in a webpage.
</li>
<li>
In a HTML file, elements composing the webpage are created,
delineated by <u>tags</u>. For instance a title of level 1 is
represented by the <code>h1</code> tag, a paragraph with the
<code>p</code> tag, an image by the <code>img</code> tag and so on.
</li>
<li>
It is impossible to create a d3.js visualization without basic
knowledge on html.
<a href="https://www.w3schools.com/html/">This tutorial</a> by
W3School can be a good starting point in my opinion.
</li>
</ul>
<br />
<code>→ Example:</code>
<div class="row">
<div
class="col-lg-5 bg-light"
style="padding: 50px"
id="res-allType"
></div>
<div class="col-lg-7">
<aside
style="position: -webkit-sticky; position: sticky; top: 120px"
>
← Edit me!
</aside>
<pre
class="language-html"
><code id="code-allType" contenteditable="true"><xmp><!DOCTYPE html>
<!-- Add a title -->
<h1>First html document</h1>
<!-- Add a bit of text -->
<p>This is my first sentence</p>
<!-- Add a link -->
<p>This is <a href="https://www.d3-graph-gallery.com">a link to the d3 graph gallery</a></p>
</xmp></code></pre>
</div>
</div>
<br /><br />
<code>→ Try:</code>
<ul>
<li>
Copy and paste the code above in a local file. Call it something
like <code>test.html</code>. Open it with a browser. You've created
your first website!
</li>
</ul>
</div>
</section>
<script>
// Read the JS fragment at the beginning. Read it again if it changes
myHtmlParser("code-allType", "res-allType");
document
.getElementById("code-allType")
.addEventListener("input", function () {
d3.select("#res-allType").html("");
myHtmlParser("code-allType", "res-allType");
});
</script>
<!-- ================================================================================= -->
<!-- ==================== CSS ==================== -->
<section id="css">
<div class="container">
<h1>Custom document style with <code>CSS</code></h1>
<hr />
<code>→ Explanation:</code>
<br />
<ul style="margin-top: 5px">
<li>
<a href="https://en.wikipedia.org/wiki/Cascading_Style_Sheets"
>CSS</a
>
stands for <u>Cascading Style Sheet</u>. It allows to apply specific
styles to the elements created using <code>html</code> before.
</li>
<li>
As for html, it is impossible to create a d3.js visualization
without basic knowledge on <code>css</code>. If it is new for you,
check this
<a href="https://www.w3schools.com/css/default.asp">tutorial</a>.
</li>
</ul>
<br />
<code>→ Example:</code>
<div class="row">
<div
class="col-lg-5 bg-light"
style="padding: 50px"
id="res-css"
></div>
<div class="col-lg-7">
<aside
style="position: -webkit-sticky; position: sticky; top: 120px"
>
← Edit me!
</aside>
<pre
class="language-html"
><code id="code-css" contenteditable="true"><xmp><!DOCTYPE html>
<!-- Apply specific style to the elements that have the class `inGreen` -->
<style>
.inGreen { color: green; }
</style>
<!-- Add a title. Note that the class 'inGreen' is given to this title -->
<h1 class="inGreen">First html document</h1>
<!-- Add a bit of text -->
<p>This is my first sentence</p>
<!-- Add a link -->
<p>This is <a href="https://www.d3-graph-gallery.com">a link to the d3 graph gallery</a></p>
</xmp></code></pre>
</div>
</div>
<br />
<code>→ Try:</code>
<ul style="margin-top: 5px">
<li>
Give the class <code>inGreen</code> to one of the paragraph
<code>p</code>
</li>
<li>
Create a new class for the first sentence of the document. Change
its font size with <code>font-size: 20px</code> in css.
</li>
</ul>
</div>
</section>
<script>
// Read the JS fragment at the beginning. Read it again if it changes
myHtmlParser("code-css", "res-css");
document
.getElementById("code-css")
.addEventListener("input", function () {
d3.select("#res-css").html("");
myHtmlParser("code-css", "res-css");
});
</script>
<!-- ================================================================================= -->
<!-- ==================== SVG ==================== -->
<section id="svg">
<div class="container">
<h1>Build shapes with <code>SVG</code></h1>
<hr />
<code>→ Explanation:</code>
<br />
<ul style="margin-top: 5px">
<li>
<a href="https://en.wikipedia.org/wiki/Scalable_Vector_Graphics"
>SVG</a
>
stands for <u>Scalable Vector Graphic</u>. It is a vector image
format. Basically, it is a language that allows to build shapes with
code.
</li>
<li>
A d3.js chart is actually a set of <code>svg</code> shapes put
together. For instant, a scatterplot is just composed by several
circles as the one shown below.
</li>
<li>
This <a href="graph/shape.html">document</a> of the d3 graph gallery
showcases the different shapes offered by Svg.
</li>
</ul>
<br />
<code>→ Example:</code>
<div class="row">
<div
class="col-lg-5 bg-light"
style="padding: 50px"
id="res-svg"
></div>
<div class="col-lg-7">
<aside
style="position: -webkit-sticky; position: sticky; top: 120px"
>
← Edit me!
</aside>
<pre
class="language-html"
><code id="code-svg" contenteditable="true"><xmp><!DOCTYPE html>
<!-- Add a title -->
<h1>First html document</h1>
<!-- Add a bit of text -->
<p>This is my first sentence</p>
<!-- Add a svg shape -->
<svg>
<circle style="fill: #69b3a2" stroke="black" cx=50 cy=50 r=40></circle>
</svg>
</xmp></code></pre>
</div>
</div>
<br />
<code>→ Try:</code>
<br />
<ul style="margin-top: 5px">
<li>
Modify the arguments of in the <code>svg</code> call to understand
what feature they control.
</li>
<li>Try to draw another type of shape using the cheat sheet below</li>
</ul>
<pre
class="language-html"
><code><xmp><line x1="0" y1="0" x2="10" y2="10" stroke="black"></line>
<rect x="0" y="0" width="10" height="10"></rect>
<circle cx="5" cy="5" r="5"></circle>
<ellipse cx="10" cy="5" rx="10" ry="5"></ellipse>
<polygon points="0,0 10,5 20,0 20,20 10,15 0,20"></polygon>
<polyline points="0,0 10,5 20,0 20,20 10,15 0,20" stroke="black"></polyline>
<path d="M65,10 a50,25 0 1,0 50,25"></path>
</xmp></code></pre>
<p style="text-align: right">
<a
style="font-size: 9px"
href="https://codepen.io/chriscoyier/pen/dXKxvv"
>Example source</a
>
</p>
</div>
</section>
<script>
// Read the JS fragment at the beginning. Read it again if it changes
myHtmlParser("code-svg", "res-svg");
document
.getElementById("code-svg")
.addEventListener("input", function () {
d3.select("#res-svg").html("");
myHtmlParser("code-svg", "res-svg");
});
</script>
<!-- ================================================================================= -->
<!-- ==================== JAVASSCRIPT AND D3 ==================== -->
<section id="d3" class="bg">
<div class="container">
<h1>
Modify elements with <code>Javascript</code> and <code>D3.js</code>
</h1>
<hr />
<code>→ Explanation:</code>
<br />
<ul style="margin-top: 5px">
<li>
<a href="https://en.wikipedia.org/wiki/JavaScript">JavaScript</a> is
one of the three core technologies of the World Wide Web. It enables
<u>interactivity</u> in webpages.
</li>
<li>
<a href="">D3.js</a> is a javascript library particularly useful for
data visualization. It allows to create, select and modify elements.
</li>
<li>
In the example below, d3 is used to select the circle with a class
<code>target</code> and modify its <code>stroke-width</code>.
</li>
<li>
It is not very impressive yet. But we will use the same kind of
process to set the position of hundreds of circle and get a
scatterplot.
</li>
</ul>
<br />
<code>→ Example:</code>
<div class="row">
<!-- ==================== GRAPH SECTION = WHERE THE GRAPH APPEARS ==================== -->
<div class="col-lg-5 .align-middle">
<div style="position: -webkit-sticky; position: sticky; top: 120px">
<div class="bg-light" id="res-basicTrigger"></div>
</div>
</div>
<!-- ==================== CODE SECTION = WHERE THE CODE APPEARS ==================== -->
<div class="col-lg-7 text-center .align-middle">
<!-- ========= show html code ============== -->
<aside
style="position: -webkit-sticky; position: sticky; top: 120px"
>
← Edit me!
</aside>
<pre
class="language-html"
><code id="html-basicTrigger" contenteditable="true"><xmp><!DOCTYPE html>
<h1>First html document</h1>
<!-- Add a bit of text -->
<p>This is my first sentence</p>
<!-- Add a svg shape. Note that the 'target' class is attributed to the circle -->
<svg>
<circle class="target" style="fill: #69b3a2" stroke="black" cx=50 cy=50 r=40></circle>
</svg>
<!-- Load d3.js -->
<script src="https://d3js.org/d3.v4.js"></script>
</xmp></code></pre>
<!-- ==================================== -->
<!-- ========= show JS code ============== -->
<pre
class="language-js"
><code id="js-basicTrigger" contenteditable="true"><xmp><script>
d3
.select(".target") // select the elements that have the class 'target'
.style("stroke-width", 8) // change their style: stroke width is not equal to 8 pixels
</script></xmp></code></pre>
<!-- ==================================== -->
<!-- ==================== JAVASCRIPT SECTION : EXECUTE THIS CODE AND MAKE IT INTERACTIVE ==================== -->
<script>
// At the beginning, I read the html and JS fragments
myHtmlParser("html-basicTrigger", "res-basicTrigger");
myJSParser("js-basicTrigger", "res-basicTrigger");
// If the user change the JS fragment, I run it again:
document
.getElementById("js-basicTrigger")
.addEventListener("input", function () {
d3.select("#res-basicTrigger").html("");
myHtmlParser("html-basicTrigger", "res-basicTrigger");
myJSParser("js-basicTrigger", "res-basicTrigger");
});
// If the user change the HTML fragment, I run it again:
document
.getElementById("html-basicTrigger")
.addEventListener("input", function () {
d3.select("#res-basicTrigger").html("");
myHtmlParser("html-basicTrigger", "res-basicTrigger");
myJSParser("js-basicTrigger", "res-basicTrigger");
});
</script>
</div>
</div>
<code>→ Try:</code>
<br />
<ul style="margin-top: 5px">
<li>
Change the circle opacity with the <code>opacity</code> style that
goes between 0 and 1.
</li>
</ul>
</div>
</section>
<br />
<!-- ==================== CONSOLE.LOG ==================== -->
<section id="coord" class="bg">
<div class="container">
<h1><code>Console.log()</code> is your friend.</h1>
<hr />
<code>→ Explanation:</code>
<br />
<ul style="margin-top: 5px">
<li>
So the browser runs <code>Html</code>, <code>Css</code> and
<code>Javascript</code> code and shows the result as a webpage.
</li>
<li>
If there is something wrong, it will give notification in the
<u>console</u>.
</li>
<li>
Usually you can open the console with <u>right click</u> ->
<u>inspect element</u>
</li>
<li>
You can output stuff in the console using the
<code>console.log("sometext")</code> in your javascript code
</li>
<li>
This is obvious for people coming from web development. But isn't
for people coming from other field (R?). It is essential to be able
to debug your code.
</li>
</ul>
</div>
</section>
<!-- ==================== COORDINATE SYSTEM ==================== -->
<section id="coord" class="bg">
<div class="container">
<h1>The coordinate system</h1>
<hr />
<code>→ Explanation:</code>
<br />
<ul style="margin-top: 5px">
<li>
Building a d3.js chart starts by creating a
<code>svg</code> element. This element has a <code>width</code> and
a <code>height</code>, given in pixels.
</li>
<li>
It is important to understand that the top left corner has the
coordinate <code>x=0</code> and <code>y=0</code>. The bottom left
corner has the coordinate <code>x=0</code> and
<code>y=height</code>. The top right corner has the coordinate
<code>x=width</code> and <code>height=0</code>
</li>
</ul>
<br />
<code>→ Example:</code>
<br />
<div class="row">
<!-- ==================== GRAPH SECTION = WHERE THE GRAPH APPEARS ==================== -->
<div class="col-lg-5 .align-middle">
<div style="position: -webkit-sticky; position: sticky; top: 120px">
<div class="bg-light" id="res-coord"></div>
</div>
</div>
<!-- ==================== CODE SECTION = WHERE THE CODE APPEARS ==================== -->
<div class="col-lg-7 text-center .align-middle">
<!-- ========= show html code ============== -->
<aside
style="position: -webkit-sticky; position: sticky; top: 120px"
>
← Edit me!
</aside>
<pre
class="language-html"
><code id="html-coord" contenteditable="true"><xmp><!DOCTYPE html>
<!-- Add a svg area, empty -->
<svg id="dataviz_area" height=200 width=450></svg>
<!-- Load d3.js -->
<script src="https://d3js.org/d3.v4.js"></script>
</xmp></code></pre>
<!-- ==================================== -->
<!-- ========= show JS code ============== -->
<pre
class="language-js"
><code id="js-coord" contenteditable="true"><xmp><script>
var svg = d3.select("#dataviz_area")
svg.append("circle")
.attr("cx", 2).attr("cy", 2).attr("r", 40).style("fill", "blue");
svg.append("circle")
.attr("cx", 140).attr("cy", 70).attr("r", 40).style("fill", "red");
svg.append("circle")
.attr("cx", 300).attr("cy", 100).attr("r", 40).style("fill", "green");
</script></xmp></code></pre>
<!-- ==================================== -->
<!-- ==================== JAVASCRIPT SECTION : EXECUTE THIS CODE AND MAKE IT INTERACTIVE ==================== -->
<script>
// At the beginning, I read the html and JS fragments
myHtmlParser("html-coord", "res-coord");
myJSParser("js-coord", "res-coord");
// If the user change the JS fragment, I run it again:
document
.getElementById("js-coord")
.addEventListener("input", function () {
d3.select("#res-coord").html("");
myHtmlParser("html-coord", "res-coord");
myJSParser("js-coord", "res-coord");
});
// If the user change the HTML fragment, I run it again:
document
.getElementById("html-coord")
.addEventListener("input", function () {
d3.select("#res-coord").html("");
myHtmlParser("html-coord", "res-coord");
myJSParser("js-coord", "res-coord");
});
</script>
</div>
</div>
<code>→ Try:</code>
<br />
<ul style="margin-top: 5px">
<li>
Change the coordinate of the 3 circles to make sure you understood
how it works
</li>
</ul>
</div>
</section>
<br />
<!-- ==================== Scale ==================== -->
<section id="scale" class="bg">
<div class="container">
<h1>From data to pixel: Scales</h1>
<hr />
<code>→ Explanation:</code>
<br />
<ul style="margin-top: 5px">
<li>
Position of element is set in <u>pixel</u>. But input dataset is
<u>not</u>.
</li>
<li>
We thus need a function that <u>translate</u> a numeric variable to
a position in pixel. It is called a <code>scale</code>
</li>
<li>
If my data are percentages and my <code>svg</code> area is 400px
width. 0% → 0px. 100% → 400px. 50% → 200px.
</li>
<li>
Scale always have a <code>domain</code> (0 to 100% here) and a
<code>range</code> (0 to 400px here)
</li>
<li>
Usually the scale for the X axis is called <code>x</code>. If you
run <code>x(10)</code>, d3 returns the position in px for this value
</li>
</ul>
<br />
<code>→ Example:</code>
<div class="row">
<!-- ==================== GRAPH SECTION = WHERE THE GRAPH APPEARS ==================== -->
<div class="col-lg-5 .align-middle">
<div style="position: -webkit-sticky; position: sticky; top: 120px">
<div class="bg-light" id="res-scale"></div>
</div>
</div>
<!-- ==================== CODE SECTION = WHERE THE CODE APPEARS ==================== -->
<div class="col-lg-7 text-center .align-middle">
<!-- ========= show html code ============== -->
<aside
style="position: -webkit-sticky; position: sticky; top: 120px"
>
← Edit me!
</aside>
<pre
class="language-html"
><code id="html-scale" contenteditable="true"><xmp><!DOCTYPE html>
<!-- Add a svg area, empty -->
<svg id="viz_area" height=200 width=450></svg>
<!-- Load d3.js -->
<script src="https://d3js.org/d3.v4.js"></script>
</xmp></code></pre>
<!-- ==================================== -->
<!-- ========= show JS code ============== -->
<pre
class="language-js"
><code id="js-scale" contenteditable="true"><xmp><script>
// Select the svg area
var svg = d3.select("#viz_area")
// Create a scale: transform value in pixel
var x = d3.scaleLinear()
.domain([0, 100]) // This is the min and the max of the data: 0 to 100 if percentages
.range([0, 400]); // This is the corresponding value I want in Pixel
// Try console.log( x(25) ) to see what this x function does.
// Add 3 dots for 0, 50 and 100%
svg.append("circle")
.attr("cx", x(10)).attr("cy", 100).attr("r", 40).style("fill", "blue");
svg.append("circle")
.attr("cx", x(50)).attr("cy", 100).attr("r", 40).style("fill", "red");
svg.append("circle")
.attr("cx", x(100)).attr("cy", 100).attr("r", 40).style("fill", "green");
</script></xmp></code></pre>
<!-- ==================================== -->
<!-- ==================== JAVASCRIPT SECTION : EXECUTE THIS CODE AND MAKE IT INTERACTIVE ==================== -->
<script>
// At the beginning, I read the html and JS fragments
myHtmlParser("html-scale", "res-scale");
myJSParser("js-scale", "res-scale");
// If the user change the JS fragment, I run it again:
document
.getElementById("js-scale")
.addEventListener("input", function () {
d3.select("#res-scale").html("");
myHtmlParser("html-scale", "res-scale");
myJSParser("js-scale", "res-scale");
});
// If the user change the HTML fragment, I run it again:
document
.getElementById("html-scale")
.addEventListener("input", function () {
d3.select("#res-scale").html("");
myHtmlParser("html-scale", "res-scale");
myJSParser("js-scale", "res-scale");
});
</script>
</div>
</div>
<code>→ Try:</code>
<br />
<ul style="margin-top: 5px">
<li>
Change <code>domain</code> and <code>range</code> values to
understand how it works.
</li>
<li>
Add a Y scale to move the circles up or down. Remember 0px is on
top!
</li>
</ul>
</div>
</section>
<br />
<!-- ==================== Axis ==================== -->
<section id="axis" class="bg">
<div class="container">
<h1>Add axis</h1>
<hr />
<code>→ Explanation:</code>
<ul style="margin-top: 5px">
<li>D3 offers a few function to draw <u>axis</u> automatically.</li>
<li>
These axis are always drawn on top of a <code>scale</code>. This
scale specifies <u>where</u> the axis must be placed, and
<u>what range</u> it should indicate.
</li>
<li>
The function <code>axisBottom()</code> creates a horizontal axis,
with ticks and labels at the bottom. <code>axisLeft()</code> will be
used later for the Y axis
</li>
</ul>
<br />
<code>→ Example:</code>
<div class="row">
<!-- ==================== GRAPH SECTION = WHERE THE GRAPH APPEARS ==================== -->
<div class="col-lg-5 .align-middle">
<div style="position: -webkit-sticky; position: sticky; top: 120px">
<div class="bg-light" id="res-axis"></div>
</div>
</div>
<!-- ==================== CODE SECTION = WHERE THE CODE APPEARS ==================== -->
<div class="col-lg-7 text-center .align-middle">
<!-- ========= show html code ============== -->
<aside
style="position: -webkit-sticky; position: sticky; top: 120px"
>
← Edit me!
</aside>
<pre
class="language-html"
><code id="html-axis" contenteditable="true"><xmp><!DOCTYPE html>
<!-- Add a svg area, empty -->
<svg id="Viz_area" height=200 width=450></svg>
<!-- Load d3.js -->
<script src="https://d3js.org/d3.v4.js"></script>
</xmp></code></pre>
<!-- ==================================== -->
<!-- ========= show JS code ============== -->
<pre
class="language-js"
><code id="js-axis" contenteditable="true"><xmp><script>
// Select the svg area
var svg = d3.select("#Viz_area")
// Create a scale: transform value in pixel
var x = d3.scaleLinear()
.domain([0, 100]) // This is the min and the max of the data: 0 to 100 if percentages
.range([0, 400]); // This is the corresponding value I want in Pixel
// Show the axis that corresponds to this scale
svg.call(d3.axisBottom(x));
// Add 3 dots for 0, 50 and 100%
svg.append("circle")
.attr("cx", x(10)).attr("cy", 100).attr("r", 40).style("fill", "blue");
svg.append("circle")
.attr("cx", x(50)).attr("cy", 100).attr("r", 40).style("fill", "red");
svg.append("circle")
.attr("cx", x(100)).attr("cy", 100).attr("r", 40).style("fill", "green");
</script></xmp></code></pre>
<!-- ==================================== -->
<!-- ==================== JAVASCRIPT SECTION : EXECUTE THIS CODE AND MAKE IT INTERACTIVE ==================== -->
<script>
// At the beginning, I read the html and JS fragments
myHtmlParser("html-axis", "res-axis");
myJSParser("js-axis", "res-axis");
// If the user change the JS fragment, I run it again:
document
.getElementById("js-axis")
.addEventListener("input", function () {
d3.select("#res-axis").html("");
myHtmlParser("html-axis", "res-axis");
myJSParser("js-axis", "res-axis");
});
// If the user change the HTML fragment, I run it again:
document
.getElementById("html-axis")
.addEventListener("input", function () {
d3.select("#res-axis").html("");
myHtmlParser("html-axis", "res-axis");
myJSParser("js-axis", "res-axis");
});
</script>
</div>
</div>
<code>→ Try:</code>
<br />
<ul style="margin-top: 5px">
<li>
Change <code>domain</code> and <code>range</code> values to
understand how it works.
</li>
</ul>
</div>
</section>
<br />
<!-- ==================== MARGIN ==================== -->
<section id="margin" class="bg">
<div class="container">
<h1>Margin & translation</h1>
<hr />
<code>→ Explanation:</code>
<ul style="margin-top: 5px">
<li>
The axis position often needs to be <u>adjusted</u>. For instance,
the X axis is usually placed at the <u>bottom</u> of the chart.
</li>
<li>
This is made possible thanks to <u>translation</u>. Basically,
applying <code>.attr("transform", "translate(20,50)")</code> to an
element with translate it 20px to the right and 50px to the bottom.
</li>
<li>
A very common strategy is to apply a translation to the general
<code>svg</code> area, creating a bit of margin around the chart