Scrolling (complete) / Interactive Info Vis

UW iSchool Course INFO 474: focused on designing and building visualizations to better understand and communicate about pressing issues.

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Edited

Dec 1, 2020

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// Keep track of the section so that updates only happen when the section changes

mutable currentSection = 0

chart = {

// Overall container

const container = d3.create("div").attr("class", "scroll-container");

// Container for the narrative section

const narrativeContainer = container

.append("div")

.attr("class", "narrative-container");

// Narrative section (holds the text on the left)

const narrative = narrativeContainer.append("div").attr("class", "narrative");

// Add text

narrative

.selectAll(".section")

.data(descriptions)

.join("div")

.attr("class", "section")

.append("text")

.text(d => d);

// Visualization container

const vis = container.append("div");

const svg = vis

.append("svg")

.attr("height", height)

.attr("width", chartWidth);

// Add the axes

svg.append("g").call(xAxis);

svg.append("g").call(yAxis);

// Update function (just switches the colors)

const update = section => {

// If the section hasn't changed, don't do anything!

if (section === mutable currentSection) return;

mutable currentSection = section;

// Filter down based on month

const min_date = x.domain()[0];

const max_date = new Date(min_date.setMonth(min_date.getMonth() + section));

// fancy transition

const transition = ele =>

ele

.transition()

.duration(1000)

.delay((d, i) => {

// Calculate days betwen this date and the max date

const one_day = 24 * 60 * 60 * 1000; // hours*minutes*seconds*milliseconds

const days_between = (max_date.getTime() - d.x.getTime()) / one_day;

return 50 * (30 - days_between);

})

.attr("r", 3);

const points = svg

.selectAll("circle")

.data(ny_data.filter(d => d.x < max_date))

.join(enter =>

enter

.append("circle")

.attr("r", 0)

.call(transition)

)

.attr("cx", d => x(d.x))

.attr("cy", d => y(d.y));

};

// Add the scrolling listener

narrativeContainer.on("scroll", () => {

// Compute section

const totalHeight = narrativeContainer.node().getBoundingClientRect().top;

const offset = narrative.node().getBoundingClientRect().y;

const section = Math.floor((totalHeight - offset + 10) / sectionHeight);

update(section);

});

return container.node();

}

md`## Scales and Axes`

x = d3

.scaleTime()

.domain(d3.extent(ny_data.map(d => d.x)))

.range([margin.left, chartWidth - margin.right])

y = d3

.scaleLinear()

.domain(d3.extent(ny_data, d => d.y))

.range([height - margin.bottom, margin.top])

xAxis = g =>

.attr("transform", `translate(0,${height - margin.bottom})`)

.call(d3.axisBottom(x))

yAxis = g =>

g.attr("transform", `translate(${margin.left},0)`).call(d3.axisLeft(y))

settings = md`## Settings`

// Descriptions for each section

descriptions = [

"COVID in New York",

"March",

"April",

"May",

"June",

"July",

"August",

"September",

"October",

"November"

]

height = 400

sectionHeight = 200

narrativeWidth = 200

margin = ({ left: 100, right: 50, top: 50, bottom: 100 })

chartWidth = width - narrativeWidth - 20

import { formatted_data } from "@mkfreeman/recreating-nyt-u-s-cases-map"

ny_data = formatted_data

.filter(d => d.state_full === "New York")[0]

.data.map(d => ({ x: new Date(d.key), y: d.value }))

import { drawChart, chart_data } from "@info474/d3-small-multiples"

html`<style>

.scroll-container {

width:${width}px;

height:${height}px;

}

.narrative-container {

height:${height}px;

overflow-y:scroll;

float:left;

}

.narrative {

width:${narrativeWidth}px;

}

.vis-container {

height:${height}px;

width:${width - narrativeWidth - 20}px;

float:right;

}

.section {

height: ${sectionHeight}px;

}

.section:last-of-type {

height:${height}px;

}

</style>`

d3 = require("d3")

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