Week 6: Labeled Lines.

<!DOCTYPE html>

<html lang="en">
	<head>
		<meta charset="utf-8">
		<title>Line Chart with Multiple Lines</title>
		<style type="text/css">

body {
				background-color: white;
				font-family: Helvetica, Arial, sans-serif;
			}

h1 {
				font-size: 24px;
				margin: 0;
			}

p {
				font-size: 14px;
				margin: 10px 0 0 0;
			}

svg {
				background-color: white;
			}

path.line {
				fill: none;
				stroke: orange;
				stroke-width: 2px;
			}

.axis path,
			.axis line {
				fill: none;
				stroke: black;
				stroke-width: 1px;
			}

.axis text {
				font-family: sans-serif;
				font-size: 11px;
			}

</style>
	</head>
	<body>

<h1>CO2 Emissions by Country</h1>

<p>Carbon dioxide emissions, 1961-2010. Data not available for the entire period for all countries. Source: <a href="https://data.worldbank.org/indicator/EN.ATM.CO2E.KT?page=6">World Bank</a>, 2014</p>

//Dimensions and padding
			var width = 700;
			var height = 600;
			var margin = {top: 20, right: 10, bottom: 40, left:100};

//Set up date formatting and years
			var dateFormat = d3.time.format("%Y");

//Set up scales
			var xScale = d3.time.scale()
								.range([ margin.left, width - margin.right - margin.left ]);

var yScale = d3.scale.linear()
								.range([ margin.top, height - margin.bottom ]);

//Configure axis generators
			var xAxis = d3.svg.axis()
							.scale(xScale)
							.orient("bottom")
							.ticks(15)
							.tickFormat(function(d) {
								return dateFormat(d);
							})
							.outerTickSize([0]);

var yAxis = d3.svg.axis()
							.scale(yScale)
							.orient("left")
							.outerTickSize([0]);

//Configure line generator
			// each line dataset must have a d.year and a d.amount for this to work.
			var line = d3.svg.line()
				.x(function(d) {
					return xScale(dateFormat.parse(d.year));
				})
				.y(function(d) {
					return yScale(+d.amount);
				});

//Create the empty SVG image
			var svg = d3.select("body")
						.append("svg")
						.attr("width", width)
						.attr("height", height);

//Load data
			d3.csv("co2_emissions.csv", function(data) {

//Data is loaded in, but we need to restructure it.
				//Remember, each line requires an array of x/y pairs;
				//that is, an array of arrays, like so:
				//
				//	[ [x: 1, y: 1], [x: 2, y: 2], [x: 3, y: 3] ]
				//
				//We, however, are using 'year' as x and 'amount' as y.
				//We also need to know which country belongs to each
				//line, so we will build an array of objects that is
				//structured like this:
				/*

[
						{
							country: "Australia",
							emissions: [
										{ year: 1961, amount: 90589.568 },
										{ year: 1962, amount: 94912.961 },
										{ year: 1963, amount: 101029.517 },
										…
									   ]
						},
						{
							country: "Bermuda",
							emissions: [
										{ year: 1961, amount: 176.016 },
										{ year: 1962, amount: 157.681 },
										{ year: 1963, amount: 150.347 },
										…
									   ]
						},
						…
					 ]

*/
				//Note that this is an array of objects. Each object
				//contains two values, 'country' and 'emissions'.
				//The 'emissions' value is itself an array, containing
				//more objects, each one holding 'year' and 'amount' values.

//New array with all the years, for referencing later
				var years = ["1961", "1962", "1963", "1964", "1965", "1966", "1967", "1968", "1969", "1970", "1971", "1972", "1973", "1974", "1975", "1976", "1977", "1978", "1979", "1980", "1981", "1982", "1983", "1984", "1985", "1986", "1987", "1988", "1989", "1990", "1991", "1992", "1993", "1994", "1995", "1996", "1997", "1998", "1999", "2000", "2001", "2002", "2003", "2004", "2005", "2006", "2007", "2008", "2009", "2010"];

// or you could get this by doing:

// var years = d3.keys(data[0]).slice(0, 54-4); //

//Create a new, empty array to hold our restructured dataset
				var dataset = [];

//Loop once for each row in data
				data.forEach(function (d, i) {

var myEmissions = [];

//Loop through all the years - and get the emissions for this data element
					years.forEach(function (y) {

// If value is not empty
						if (d[y]) {
							//Add a new object to the new emissions data array - for year, amount
							myEmissions.push({
								year: y,
								amount: d[y]  // this is the value for, for example, d["2004"]
 							});
						}

});

//Create new object with this country's name and empty array
					// d is the current data row... from data.forEach above.
					dataset.push( {
						country: d.countryName,
						emissions: myEmissions  // we just built this!
						} );

});

//Uncomment to log the original data to the console
				// console.log(data);

//Uncomment to log the newly restructured dataset to the console
				console.log(dataset);

//Set scale domains - max and mine of the years
				xScale.domain(
					d3.extent(years, function(d) {
						return dateFormat.parse(d);
					}));

// max of emissions to 0 (reversed, remember)
				yScale.domain([
					d3.max(dataset, function(d) {
						return d3.max(d.emissions, function(d) {
							return +d.amount;
						});
					}),
					0
				]);

//Make a group for each country
				var groups = svg.selectAll("g")
					.data(dataset)
					.enter()
					.append("g");

//Append a title with the country name (so we get easy tooltips)
				groups.append("title")
					.text(function(d) {
						return d.country;
					});

//Within each group, create a new line/path,
				//binding just the emissions data to each one
				groups.selectAll("path")
					.data(function(d) { // because there's a group with data already...
						return [ d.emissions ]; // it has to be an array for the line function
					})
					.enter()
					.append("path")
					.attr("class", "line")
					.attr("d", line);

/*groups.append('text.labels')
							.datum(function(d) {
							if (dataset[0] === "China" || dataset[0] === "United States") {
							var j = d.emissions.length - 1;
							while(d.emissions[j].position == 0 && j > 0) { j--; }
							return {country: d.country, emissions: d.amount[j]};
								}
							})
						  .attr("transform", function(d) {
						  return "translate(" + xScale(dataset[1].year) + "," + yScale(dataset[1].amount) + ")";
							})
							.attr("x", 3)
							.attr("dy", ".35em")
							.text(function(d) { return dataset[0]; });*/

//Axes
				svg.append("g")
					.attr("class", "x axis")
					.attr("transform", "translate(0," + (height - margin.bottom) + ")")
					.call(xAxis);

svg.append("g")
					.attr("class", "y axis")
					.attr("transform", "translate(" + margin.left + ",0)")
					.call(yAxis);

svg.append("text")
					.attr("transform", "translate(" + (width - margin.left) + "," + yScale(dataset[40].emissions[49].amount) + ")")
					.attr("dy", ".35em")
					.attr("text-anchor", "start")
					.attr("font-size", "14")
					.attr("font-weight", "bold")
					.style("fill", "rgba(155,155,155,1)")
					.text("China");

svg.append("text")
					.attr("transform", "translate(" + (width - margin.left) + "," + yScale(dataset[207].emissions[49].amount) + ")")
					.attr("dy", ".35em")
					.attr("text-anchor", "start")
					.attr("font-size", "14")
					.attr("font-weight", "bold")
					.style("fill", "rgba(155,155,155,1)")
					.text("United States");

}); // end of data csv

</script>

</body>
</html>

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