Global Development Example
Interactive timelines for global health and economic development data: grab a point to drag it through time! Based on the DimpVis technique by Brittany Kondo and Christopher Collins, University of Ontario Institute of Technology (2014).
Vega JSON Specification <>
{
"$schema": "https://vega.github.io/schema/vega/v5.json",
"description": "An interactive scatter plot of global health statistics by country and year.",
"width": 800,
"height": 600,
"padding": 5,
"data": [
{
"name": "gapminder",
"url": "data/gapminder.json"
},
{
"name": "clusters",
"values": [
{"id": 0, "name": "South Asia"},
{"id": 1, "name": "Europe & Central Asia"},
{"id": 2, "name": "Sub-Saharan Africa"},
{"id": 3, "name": "America"},
{"id": 4, "name": "East Asia & Pacific"},
{"id": 5, "name": "Middle East & North Africa"}
]
},
{
"name": "country_timeline",
"source": "gapminder",
"transform": [
{"type": "filter", "expr": "timeline && datum.country == timeline.country"},
{"type": "collect", "sort": {"field": "year"}}
]
},
{
"name": "thisYear",
"source": "gapminder",
"transform": [
{"type": "filter", "expr": "datum.year == currentYear"}
]
},
{
"name": "prevYear",
"source": "gapminder",
"transform": [
{"type": "filter", "expr": "datum.year == currentYear - stepYear"}
]
},
{
"name": "nextYear",
"source": "gapminder",
"transform": [
{"type": "filter", "expr": "datum.year == currentYear + stepYear"}
]
},
{
"name": "countries",
"source": "gapminder",
"transform": [
{"type": "aggregate", "groupby": ["country"]}
]
},
{
"name": "interpolate",
"source": "countries",
"transform": [
{
"type": "lookup",
"from": "thisYear", "key": "country",
"fields": ["country"], "as": ["this"],
"default": {}
},
{
"type": "lookup",
"from": "prevYear", "key": "country",
"fields": ["country"], "as": ["prev"],
"default": {}
},
{
"type": "lookup",
"from": "nextYear", "key": "country",
"fields": ["country"], "as": ["next"],
"default": {}
},
{
"type": "formula",
"as": "target_fertility",
"expr": "interYear > currentYear ? datum.next.fertility : (datum.prev.fertility||datum.this.fertility)"
},
{
"type": "formula",
"as": "target_life_expect",
"expr": "interYear > currentYear ? datum.next.life_expect : (datum.prev.life_expect||datum.this.life_expect)"
},
{
"type": "formula",
"as": "inter_fertility",
"expr": "interYear==2000 ? datum.this.fertility : datum.this.fertility + (datum.target_fertility-datum.this.fertility) * abs(interYear-datum.this.year)/5"
},
{
"type": "formula",
"as": "inter_life_expect",
"expr": "interYear==2000 ? datum.this.life_expect : datum.this.life_expect + (datum.target_life_expect-datum.this.life_expect) * abs(interYear-datum.this.year)/5"
}
]
},
{
"name": "trackCountries",
"on": [
{"trigger": "active", "toggle": "{country: active.country}"}
]
}
],
"signals": [
{ "name": "minYear", "value": 1955 },
{ "name": "maxYear", "value": 2005 },
{ "name": "stepYear", "value": 5 },
{
"name": "active",
"value": {},
"on": [
{"events": "@point:pointerdown, @point:touchstart", "update": "datum"},
{"events": "window:pointerup, window:touchend", "update": "{}"}
]
},
{ "name": "isActive", "update": "active.country" },
{
"name": "timeline",
"value": {},
"on": [
{"events": "@point:pointerover", "update": "isActive ? active : datum"},
{"events": "@point:pointerout", "update": "active"},
{"events": {"signal": "active"}, "update": "active"}
]
},
{
"name": "tX",
"on": [{
"events": "pointermove!, touchmove!",
"update": "isActive ? scale('x', active.this.fertility) : tX"
}]
},
{
"name": "tY",
"on": [{
"events": "pointermove, touchmove",
"update": "isActive ? scale('y', active.this.life_expect) : tY"
}]
},
{
"name": "pX",
"on": [{
"events": "pointermove, touchmove",
"update": "isActive ? scale('x', active.prev.fertility) : pX"
}]
},
{
"name": "pY",
"on": [{
"events": "pointermove, touchmove",
"update": "isActive ? scale('y', active.prev.life_expect) : pY"
}]
},
{
"name": "nX",
"on": [{
"events": "pointermove, touchmove",
"update": "isActive ? scale('x', active.next.fertility) : nX"
}]
},
{
"name": "nY",
"on": [{
"events": "pointermove, touchmove",
"update": "isActive ? scale('y', active.next.life_expect) : nY"
}]
},
{
"name": "thisDist",
"value": 0,
"on":[{
"events": "pointermove, touchmove",
"update": "isActive ? hypot(x()-tX, y()-tY) : thisDist"
}]
},
{
"name": "prevDist",
"value": 0,
"on":[{
"events": "pointermove, touchmove",
"update": "isActive ? hypot(x()-pX, y()-pY): prevDist"
}]
},
{
"name": "nextDist",
"value": 0,
"on":[{
"events": "pointermove, touchmove",
"update": "isActive ? hypot(x()-nX, y()-nY) : nextDist"
}]
},
{
"name": "prevScore",
"value": 0,
"on": [{
"events": "pointermove, touchmove",
"update": "isActive ? ((pX-tX) * (x()-tX) + (pY-tY) * (y()-tY))/prevDist || -999999 : prevScore"
}]
},
{
"name": "nextScore",
"value": 0,
"on": [{
"events": "pointermove, touchmove",
"update": "isActive ? ((nX-tX) * (x()-tX) + (nY-tY) * (y()-tY))/nextDist || -999999 : nextScore"
}]
},
{
"name": "interYear",
"value": 1980,
"on": [{
"events": "pointermove, touchmove",
"update": "isActive ? (min(maxYear, currentYear+5, max(minYear, currentYear-5, prevScore > nextScore ? (currentYear - 2.5*prevScore/hypot(pX-tX, pY-tY)) : (currentYear + 2.5*nextScore/hypot(nX-tX, nY-tY))))) : interYear"
}]
},
{
"name": "currentYear",
"value": 1980,
"on":[{
"events": "pointermove, touchmove",
"update": "isActive ? (min(maxYear, max(minYear, prevScore > nextScore ? (thisDist < prevDist ? currentYear : currentYear-5) : (thisDist < nextDist ? currentYear : currentYear+5)))) : currentYear"
}]
}
],
"scales": [
{
"name": "x",
"type": "linear", "nice": true,
"domain": {"data": "gapminder", "field": "fertility"},
"range": "width"
},
{
"name": "y",
"type": "linear", "nice": true, "zero": false,
"domain": {"data": "gapminder", "field": "life_expect"},
"range": "height"
},
{
"name": "color",
"type": "ordinal",
"domain": {"data": "gapminder", "field": "cluster"},
"range": "category"
},
{
"name": "label",
"type": "ordinal",
"domain": {"data": "clusters", "field": "id"},
"range": {"data": "clusters", "field": "name"}
}
],
"axes": [
{
"title": "Fertility",
"orient": "bottom", "scale": "x",
"grid": true, "tickCount": 5
},
{
"title": "Life Expectancy",
"orient": "left", "scale": "y",
"grid": true, "tickCount": 5
}
],
"legends": [
{
"fill": "color",
"title": "Region",
"orient": "right",
"encode": {
"symbols": {
"enter": {
"fillOpacity": {"value": 0.5}
}
},
"labels": {
"update": {
"text": {"scale": "label", "field": "value"}
}
}
}
}
],
"marks": [
{
"type": "text",
"encode": {
"update": {
"text": {"signal": "currentYear"},
"x": {"value": 300},
"y": {"value": 300},
"fill": {"value": "grey"},
"fillOpacity": {"value": 0.25},
"fontSize": {"value": 100}
}
}
},
{
"type": "text",
"from": {"data": "country_timeline"},
"interactive": false,
"encode": {
"enter": {
"x": {"scale": "x", "field": "fertility", "offset": 5},
"y": {"scale": "y", "field": "life_expect"},
"fill": {"value": "#555"},
"fillOpacity": {"value": 0.6},
"text": {"field": "year"}
}
}
},
{
"type": "line",
"from": {"data": "country_timeline"},
"encode": {
"update": {
"x": {"scale": "x", "field": "fertility"},
"y": {"scale": "y", "field": "life_expect"},
"stroke": {"value": "#bbb"},
"strokeWidth": {"value": 5},
"strokeOpacity": {"value": 0.5}
}
}
},
{
"name": "point",
"type": "symbol",
"from": {"data": "interpolate"},
"encode": {
"enter": {
"fill": {"scale": "color", "field": "this.cluster"},
"size": {"value": 150}
},
"update": {
"x": {"scale": "x", "field": "inter_fertility"},
"y": {"scale": "y", "field": "inter_life_expect"},
"fillOpacity": [
{
"test": "datum.country==timeline.country || indata('trackCountries', 'country', datum.country)",
"value": 1
},
{"value": 0.5}
]
}
}
},
{
"type": "text",
"from": {"data": "interpolate"},
"interactive": false,
"encode": {
"enter": {
"fill": {"value": "#333"},
"fontSize": {"value": 14},
"fontWeight": {"value": "bold"},
"text": {"field": "country"},
"align": {"value": "center"},
"baseline": {"value": "bottom"}
},
"update": {
"x": {"scale": "x", "field": "inter_fertility"},
"y": {"scale": "y", "field": "inter_life_expect", "offset": -7},
"fillOpacity": [
{
"test": "datum.country==timeline.country || indata('trackCountries', 'country', datum.country)",
"value": 0.8
},
{"value": 0}
]
}
}
}
]
}