06_each.html

<!DOCTYPE html>
<html lang="en">
	<head>
		<meta charset="utf-8">
		<title>D3: Using each() to run an arbitrary function on each element in a selection</title>
		<script src="https://d3js.org/d3.v4.min.js"></script>
		<style type="text/css">
			/* No style rules here yet */
		</style>
	</head>
	<body>

		<p>
			<input type="button" value="Change each point">
			<input type="button" value="Refresh">
		</p>

		<script type="text/javascript">

			//Width and height
			var w = 600;
			var h = 500;
			var padding = 40;
			
			//Dynamic, random dataset
			var dataset = [];					//Initialize empty array
			var numDataPoints = 400;			//Number of dummy data points to create
			var xRange = 1000;					//Max range of new x values
			var yRange = 1000;					//Max range of new y values
			for (var i = 0; i < numDataPoints; i++) {					//Loop numDataPoints times
				var newNumber1 = Math.floor(Math.random() * xRange);	//New random integer
				var newNumber2 = Math.floor(Math.random() * yRange);	//New random integer
				dataset.push([newNumber1, newNumber2]);					//Add new number to array
			}

			//console.table(dataset);

			//Create scale functions
			var xScale = d3.scaleLinear()
								 .domain([0, 1000])
								 .range([padding, w - padding / 2]);

			var yScale = d3.scaleLinear()
								 .domain([0, 1000])
								 .range([h - padding, padding / 2]);

			//Define X axis
			var xAxis = d3.axisBottom()
							  .scale(xScale)
							  .ticks(10);

			//Define Y axis
			var yAxis = d3.axisLeft()
							  .scale(yScale)
							  .ticks(10);

			//Create SVG element
			var svg = d3.select("body")
						.append("svg")
						.attr("width", w)
						.attr("height", h);

			//Create circles
			var allCircles = svg.selectAll("circle")
			   .data(dataset)
			   .enter()
			   .append("circle")
			   .attr("cx", function(d) {
			   		return xScale(d[0]);
			   })
			   .attr("cy", function(d) {
			   		return yScale(d[1]);
			   })
			   .attr("r", 3)
			   .attr("fill", "#b8c8d8");
			

			//Create X axis
			svg.append("g")
				.attr("class", "axis")
				.attr("transform", "translate(0," + (h - padding) + ")")
				.call(xAxis);
			
			//Create Y axis
			svg.append("g")
				.attr("class", "axis")
				.attr("transform", "translate(" + padding + ",0)")
				.call(yAxis);

			//On button click, execute a function for each circle in the allCircles selection
			d3.selectAll("input")
				.on("click", function() {
					var view = d3.select(this).node().value;
					switch (view) {

						case "Change each point":

							allCircles.each(freakOut);  //Hold on to your hats!

						break;						

						case "Refresh":

							allCircles.each(sober);

						break;
				}
				});


			//Define the sober function
			var sober = function(d, i){
				d3.select(this)
					.transition()
					.delay(i * 5)
					.duration(10)
					.ease(d3.easeBackIn)
					.attr("fill", "#b8c8d8")
					.attr("r", 3);
			};

			//Define the freakOut function
			var freakOut = function(d, i) {

				//Since this function will be called by 'each()',
				//it will be aware of each element on which it operates.
				//The 'this' context will be updated, and d and i will
				//be populated with the associated values.

				var colors = d3.schemeCategory20;
				var colorIndex = Math.round(Math.random() * 20);

				d3.select(this)
					.transition()
					.delay(i * 25)
					.duration(2000)
					.ease(d3.easeElasticOut)
					.attr("fill", colors[colorIndex])
					.attr("r", 10);

			};

		</script>
	</body>
</html>