D3.JS: DATA-DRIVEN DELIGHT

Source: Mike Bostock's Craig Retroazimuthal

Anna Powell-Smith, Front-End London, 17/1/13

HELLO



Today's slides: http://anna.ps/talks/fel

WHAT IS D3?

A JavaScript library for creating data visualisations
"jQuery for SVG"


WHENCE D3?


2005: Prefuse (Java, Heer, Berkeley)
|
2007: Flare (ActionScript, Heer, Berkeley)
|
2009: Protovis (JavaScript, Heer/Bostock, Stanford)
|
2011: D3 (JavaScript, Heer/Bostock, Stanford)

WHY D3?

Other libraries: proprietary methods
Convenient, but tricky to extend or debug
var plot1 = $.jqplot('chart1', [[3,7,9,1,4,6,8,2,5]]);

WHY D3?

D3: solves the fundamental problem
Bind data directly to the DOM
var dataset = [ 5, 10, 13, 19, 21, 25, 22, 18, ...];
			
var svg = d3.select("body").append("svg")
    .attr("width", 500).attr("height", 100);
    
svg.selectAll("rect").data(dataset)
  .enter().append("rect")
  .attr("x", function(d, i) {
    return i * (w / dataset.length);
  })
  .attr("y", function(d) {
    return h - (d * 4);
  })
  .attr("width", w / dataset.length - barPadding)
  .attr("height", function(d) {
    return d * 4;
  })
  .attr("fill", function(d) {
    return "rgb(0, 0, " + (d * 10) + ")";
  });

WHY D3?

View and debug the output with Firebug

THE D3 DIFFERENCE


1. Solves fundamental problem: manipulate DOM with data

2. Web standards: style with CSS, JS events, DevTools/Firebug

3. Fast, simple and efficient

4. Fantastic support for animations and transitions

5. Encourages code modularity with plugins

BUT IS IT AWESOME??

EXAMPLES

Source: Mike Bostock's streamgraph example

EXAMPLES

Source: Mike Bostock's force-directed graph example

EXAMPLES

Source: Mike Bostock's Chloropleth Map

EXAMPLES

Source: Mike Bostock's OMG Particles

DATA BINDING

jQuery-like selectors to simplify DOM API

var dataset = [ 5, 10, 13, 19, 21, 25, 22, 18, ...];
    		
var svg = d3.select("body").append("svg")
    .attr("width", 500).attr("height", 100);
    
svg.selectAll("#graph rect.cities").data(dataset)
  .enter().append("rect")
  .attr("x", function(d, i) {
    return i * (w / dataset.length);
  })
  .attr("y", function(d) {
    return h - (d * 4);
  })
  .attr("width", w / dataset.length - barPadding)
  .attr("height", function(d) {
    return d * 4;
  })
  .attr("fill", function(d) {
    return "rgb(0, 0, " + (d * 10) + ")";
  });

DATA BINDING

Set properties using functions of data - very powerful

var dataset = [ 5, 10, 13, 19, 21, 25, 22, 18, ...];
        	
var svg = d3.select("body").append("svg")
    .attr("width", 500).attr("height", 100);
    
svg.selectAll("#graph rect.cities").data(dataset)
  .enter().append("rect")
  .attr("x", function(d, i) {
    return i * (w / dataset.length);
  })
  .attr("y", function(d) {
    return h - (d * 4);
  })
  .attr("width", w / dataset.length - barPadding)
  .attr("height", function(d) {
    return d * 4;
  })
  .attr("fill", function(d) {
    return "rgb(0, 0, " + (d * 10) + ")";
  });

SCALES


Source: Jerome Cukier's D3, Scales and Colour

TRANSITIONS


    				
svg.selectAll("rect").data(dataset)
  .transition().duration(2500)
  .attr("y", function(d) {return h - yScale(d); })
  .attr("height", function(d) { return yScale(d); })
  .attr("fill", function(d) {
	return "rgb(0, 0, " + (d * 10) + ")";
  });

LAYOUTS

Bundle 
Chord 
Cluster 
Force
Hierarchy 
Histogram 
Pack
Partition
Pie
Stack
Tree
Treemap

LIMITATIONS


1. SVG: no IE8 support, older Android

2. Not easy for simple graphs: but try Rickshaw.js, NVD3

3. Can't hide underlying data: always visible 

IE8 APPROACHES


1. Aight - stops D3 breaking altogether in IE8

2. R2D3 - use Raphael and D3 together for visualisation

3. Feature detection and use alternative libraries (or tables)

document.implementation.hasFeature
 ("http://www.w3.org/TR/SVG11/feature#BasicStructure", "1.1"); 
        

POSSIBILITIES: GEO

Source: CartoDB makes D3 maps a breeze

POSSIBILITIES: MATHS


POSSIBILITIES: 
LOVELY INTERACTION


RESOURCES: 

GETTING STARTED

Getting past the conceptual hurdles

  d3.select("body").selectAll("p")
        .data(dataset)
        .enter()
        .append("p")
        .text("New paragraph!");

SCOTT MURRAY'S TUTORIALS

Free at alignedleft.com

SCOTT MURRAY'S BOOK


MIKE BOSTOCK'S PAPER

RESOURCES:

INTERMEDIATE

Jerome Cukier's D3 cheat sheet (pdf)

RESOURCES:

INTERMEDIATE

bl.ocks.org: follow Mike Bostock & Jason Davies

RESOURCES:

ADVANCED


BEER!


D3 London Drinks
Wednesday 30th January

QUESTIONS?

WORK FOR MYSOCIETY

Developers needed

d3 intro at front end london

By annaps

d3 intro at front end london

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