shirley wu

(@sxywu)

workshop

I'm an independent creator

of data visualizations.

Hi, I'm Shirley!

 

 

 

 

what we're
building today

 

 

 

 

 

 

 

 

 

 

what we'll be using

for creating

data visualizations for the web

for building

interactive single-page applications

but why use them together?

 

 

 

 

 

 

 

 

the D3 library is really big

and has a lot of functionality

 

 

 

 

 

 

 

 

 

raw data scales x / y
width / height
angle / radius
color
raw data forces
hierarchies
x / y positions
raw data geographies x / y positions
raw data chords
shapes
svg path commands

brush

drag

zoom + pan

Vue's declarative rendering and reactivity system are great replacements for

D3's enter-update-exit and dispatch system

declarative rendering

<svg>
  <path v-for='d in arcs' :key='d.id' :d='d.path' :fill='d.fill' stroke='#fff' />
</svg>
const svg = d3.select('svg')

const path = svg.selectAll('path')
  .data(arcs, d => d.id);

path.exit().remove()

path.enter().append()
  .attr('stroke', '#fff')
  .merge(path)
  .attr('d', d => d.path)
  .attr('fill', d => d.fill)
  

reactivity system

<template>
  <svg :width='width' :height='height'>
    <path v-for='d in arcs' :d='d.path' />
  </svg>
</template>

<script>
export default {
  name: 'areachart',
  data() {
    return {
      width: 1000, height: 300,
      movies: [],
      arcs: [],
    }
  },
  watch: {
    movies() { ... }
  },
}
</script>

tells Vue to track changes for datum

when datum changes, do something

v-bind: (or :) tells Vue to automatically update if datum changes

1. translate raw data into screen space

  • release date → x-position
  • box office → y-position
  • metascore → color

2. calculate svg paths for drawing shapes

3. render to DOM

our custom visualization

1. translate raw data into screen space

  • release date → x-position
  • box office → y-position
  • metascore → color

2. calculate svg paths for drawing shapes

3. render to DOM

our custom visualization

1. d3 scales

2. d3 shapes

3. declarative rendering

scales

map from raw data (domain)

to display (range)

const width = 800
const height = 600
const data = [
  {date: new Date('01-01-2015'), boxOffice: 2349800},
  {date: new Date('01-01-2017'), boxOffice: 32487652},
  ...
]

const min = d3.min(data, d => d.date)
const max = d3.max(data, d => d.date)
const xScale = d3.scaleTime()
  .domain([min, max])
  .range([0, width])

// d3.extent returns [min, max]
const extent = d3.extent(data, d => d.boxOffice)
const yScale = d3.scaleLinear()
  .domain(extent)
  .range([height, 0])
  1. get min/max of date
  2. initialize time scale
  3. pass date min/max to domain
  4. map to min/max width in range

shapes

const data = [
  {date: new Date('01-01-2015'), boxOffice: 2349800},
  {date: new Date('01-01-2017'), boxOffice: 32487652},
  …
]

const area = d3.area()
  .x(d => xScale(d.date))
  .y1(d => yScale(d.boxOffice))
  .y0(yScale(0))

area(data)

generates SVG or Canvas path commands to draw shape

  1. initialize
  2. specify x/y accessor
  3. specify baseline
  4. generate SVG path string

d3.area()

pass in array of points, draws line through points and fills area underneath

exercise time!

Set up AreaChart.vue

  1. in App.vue, pass movies into AreaChart.vue
  2. in AreaChart.vue, receive movies as props
  3. Watch for changes on movies

 

release date → scaleTime  x-position
box office → scaleLinear  y-position
metascore → scaleSequential  color

 

use d3.area() to create an array of objects

each object has id, path, fill

exercise time!

Draw SVG paths with Vue

exercise time!

Interactions

Set up D3 brush in Histogram.vue

  1. Create empty <g> element
  2. Initialize d3.brushX() with bounds
  3. Pass <g> element to D3 brush

exercise time!

In Histogram.vue

  1. On brush, calculate bounds             

In App.vue

  1. Filter for movies within bounds
  2. Set filtered movies in data()
  3. Update AreaChart.vue and Histogram.vue with filtered movies

exercise time!

more workshops

thank you!

@sxywu

Vue & D3 Workshop

By Shirley Wu

Vue & D3 Workshop

For jsconf.jp, 12/1/2019

  • 214
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