Demonstration of transforming CSV data using D3
For NICAR Beginning D3, 2017
Charts forked from d3indepth‘s block: DOM Manipulation
forked from darlacameron‘s block: 2. Transforming data
forked from darlacameron‘s block: 3. Drawing shapes
forked from anonymous‘s block: Time series chart with real data
forked from jmuyskens‘s block: Multiple time series chart with real data
forked from jmuyskens‘s block: Single time series chart with real data
var parseTime = d3.timeParse('%a %b %d %H:%M:%S +0000 %Y');
var formatTime = d3.timeFormat('%Y-%m-%d');
var parseFormattedTime = d3.timeParse('%Y-%m-%d');
var lineChart = function(data){
// set the dimensions and margins of the graph
var margin = {top: 20, right: 20, bottom: 60, left: 50},
width = 606 - margin.left - margin.right,
height = 181 - margin.top - margin.bottom;
data = data.map(function(d) {
d.date = parseTime(d.created_at)
return d;
}).filter(function(d) {
return d.date >= d3.timeParse("%Y")("2017")
});
// NEST
var nestedData = d3.nest()
.key(function(d) { return formatTime(d.date); })
.sortKeys(d3.ascending)
.rollup(function(values) { return values.length; })
.entries(data);
var nestedDataMap = d3.nest()
.key(function(d) { return formatTime(d.date); })
.sortKeys(d3.ascending)
.rollup(function(values) { return values.length; })
.map(data);
console.log(nestedDataMap, nestedDataMap['$2017-03-01']);
var dateRange = [];
var date = new Date(Date.UTC(2017, 0, 2));
var endDate = new Date(Date.UTC(2017, 2, 2));
while (date <= endDate) {
dateRange.push(formatTime(date));
date = new Date(date.setDate(date.getDate() + 1));
}
console.log(dateRange);
/*nestedData = dateRange.map(function(d) {
if (nestedDataMap.hasOwnProperty("$" + d)) {
return {key: d, value: nestedDataMap["$" + d] };
} else {
return {key: d, value: 0}
}
});*/
console.log(nestedData.length);
// set the ranges
var xScale = d3.scaleTime().range([0, width]);
var yScale = d3.scaleLinear().range([height, 0]);
// define the line
var line = d3.line()
.x(function(d) { return xScale(parseFormattedTime(d.key)); })
.y(function(d) { return yScale(d.value); });
//add a new svg to hold the chart
var svg = d3.select("body").append("svg")
.attr("width", width + margin.left + margin.right)
.attr("height", height + margin.top + margin.bottom)
.append("g")
.attr("transform", "translate(" + margin.left + "," + margin.top + ")");
// Scale the range of the data
xScale.domain(d3.extent(data, function(d) { return d.date; }));
yScale.domain(d3.extent(nestedData, (d) => d.value));
// Add the X Axis
svg.append("g")
.attr("transform", "translate(0," + height + ")")
.call(d3.axisBottom(xScale));
// Add the Y Axis
svg.append("g")
.call(d3.axisLeft(yScale));
//console.log(line(nestedData))
// Add the line path
svg.selectAll("path.tweetline")
.data([nestedData])
.enter().append('path')
.attr("class", "tweetline")
.attr("d", line);
};
<!DOCTYPE html>
<meta charset="utf-8">
<head>
<title>Transforming data</title>
</head>
<style>
body {
font-family: "Helvetica Neue", Helvetica, sans-serif;
font-size: 14px;
}
path {
fill: none;
stroke: #aaa;
}
.tweetline {
stroke-width:2px;
}
</style>
<body>
<script src="//d3js.org/d3.v4.min.js"></script>
<script src="script.js"></script>
<script>
d3.csv("realdonaldtrumpsinceelection.csv", function(error, data) {
if (error) throw error;
lineChart(data);
});
</script>
</body>
</html>