This chart was part of the Week 3 Workout Wednesday challenge.
Dataset
The dataset can be found on the Workout Wednesday link above.
Additional fields created
None
Fields used
- Date
- Close
- Company
Specification
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{
"$schema": "https://vega.github.io/schema/vega-lite/v5.json",
"data": {"name": "dataset"},
"layer": [
{
"description": "set the date points to facilitate the click event & default value",
"params": [
{
"name": "select",
"value": [
{
"x": {
"year": 2020,
"month": 11,
"date": 1
}
}
],
"select": {
"type": "point",
"encodings": ["x"],
"on": "click",
"nearest": true
}
}
],
"mark": "point",
"encoding": {
"x": {
"field": "Date",
"type": "temporal"
},
"opacity": {"value": 0}
}
},
{
"description": "when the date is selected, recalculated the % change",
"transform": [
{
"lookup": "symbol",
"from": {
"param": "select",
"key": "symbol"
}
},
{
"calculate": "datum.select && datum.select.Close > 0 ?
(datum.Close - datum.select.Close)/datum.select.Close : 0",
"as": "selected_price"
}
],
"layer": [
{
"description": "draw the line chart for the price change",
"mark": "line",
"encoding": {
"x": {
"field": "Date",
"type": "temporal"
},
"y": {
"field": "selected_price",
"type": "quantitative",
"axis": {"format": "%"}
},
"color": {
"field": "Company",
"type": "nominal",
"legend": null
}
}
},
{
"description": "determine the price value at the end of date range",
"encoding": {
"x": {
"aggregate": "max",
"field": "Date",
"type": "temporal"
},
"y": {
"aggregate": {
"argmax": "Date"
},
"field": "selected_price",
"type": "quantitative"
},
"color": {
"field": "Company",
"type": "nominal"
}
},
"layer": [
{
"description": "draw a circle at the end of the date range",
"mark": {"type": "circle"}
},
{
"description": "add text for the company at the end of the date range",
"mark": {
"type": "text",
"align": "left",
"dx": 4
},
"encoding": {
"text": {
"field": "Company",
"type": "nominal"
}
}
}
]
},
{
"transform": [
{
"filter": {
"param": "select"
}
}
],
"encoding": {
"x": {
"field": "Date",
"type": "temporal",
"timeUnit": "yearmonth"
}
},
"layer": [
{
"description": "show the line and text for the selected month",
"mark": {
"type": "text",
"align": "right",
"fontWeight": 100,
"dx": -5
},
"encoding": {
"text": {
"field": "Date",
"timeUnit": "yearmonth"
},
"y": {"value": 10},
"color": {
"value": "#7D7A78"
}
}
}
]
},
{
"layer": [
{
"transform": [
{
"filter": {
"param": "select"
}
}
],
"description": "add vertical rule for the selected month",
"mark": {
"type": "rule",
"strokeWidth": 0.5,
"strokeDash": [1, 2]
},
"encoding": {
"x": {
"field": "Date",
"type": "temporal"
},
"color": {
"value": "#7D7A78"
}
}
},
{
"transform": [
{
"filter": {
"param": "select"
}
}
],
"description": "add horizontal line at baseline (0%)",
"mark": {
"type": "rule",
"strokeWidth": 0.5,
"strokeDash": [1, 2]
},
"encoding": {
"y": {
"field": "yaxis",
"type": "quantitative"
},
"color": {
"value": "#7D7A78"
}
}
},
{
"transform": [
{
"filter": {
"param": "select"
}
}
],
"description": "add black circle at the selected month",
"mark": {
"type": "circle",
"size": 50
},
"encoding": {
"x": {
"field": "Date",
"type": "temporal"
},
"y": {
"field": "yaxis",
"type": "quantitative"
},
"color": {
"value": "black"
}
}
}
]
}
]
}
]
}
Config
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{
"autosize": {
"type": "fit",
"contains": "padding"
},
"range": {
"category": [
"#1BA3C6",
"#BDBD22",
"#F43C63",
"#4F7CBA"
]
},
"legend": {"disable": true},
"view": {"stroke": 0},
"axis": {
"domain": false,
"grid": false,
"labelPadding": 10,
"ticks": false,
"title": null,
"labelFont": "Segoe UI",
"labelFontSize": 10,
"labelColor": "#7D7A78"
},
"text": {
"font": "Consolas",
"fontSize": 12
}
}
External references
- Interactive Index Chart - used as the starting point.
- Event Streams - used to determine the select method;
- Pyramid Pie Chart - used the color code section;
View chart
Open the Chart in the Vega Editor
you need to
clickanywhere on the chart for it to render the first time.