Cours 2

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<!DOCTYPE html>
<meta charset="utf-8">
<style>

body {
  font: 10px sans-serif;
}

.axis path, .axis line {
  fill: none;
  stroke: #000;
  shape-rendering: crispEdges;
}

.dot {
  stroke: #000;
}

.tooltip {
	position: absolute;
	width: 200px;
	height: 28px;
	pointer-events: none;
}

</style>
<body>
<script src="https://d3js.org/d3.v4.min.js"></script>
<script>

var margin = {top: 20, right: 20, bottom: 30, left: 40},
    width = 960 - margin.left - margin.right,
    height = 500 - margin.top - margin.bottom;

var x = d3.scaleLinear()
    .range([0, width]);

var y = d3.scaleLinear()
    .range([height, 0]);

var r = d3.scaleSqrt()
		.range([2,10]);
  
var xAxis = d3.axisBottom()
		.scale(x);

var yAxis = d3.axisLeft()
		.scale(y);
  
var color = d3.scaleOrdinal(d3.schemeCategory20);

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 + ")");

var tooltip = d3.select("body").append("div")
					.attr("class", "tooltip")
					.style("opacity", 0);

d3.csv('iris.csv', function(error, data){
	data.forEach(function(d){
    d.sepal_length = +d.sepal_length;
    d.sepal_width  = +d.sepal_width;
    d.petal_length = +d.petal_length;
    d.petal_width  = +d.petal_width;
	});

x.domain(d3.extent(data, function(d){
		return d.sepal_length;
	})).nice();

y.domain(d3.extent(data, function(d){
		return d.sepal_width;
	})).nice();

r.domain(d3.extent(data, function(d){
		return d.petal_length;
	})).nice();
  
  svg.append('g')
    .attr('transform', 'translate(0,' + height + ')')
    .attr('class', 'x axis')
    .call(xAxis);

svg.append('g')
    .attr('transform', 'translate(0,0)')
    .attr('class', 'y axis')
    .call(yAxis);

svg.append('text')
		.attr('x', 10)
		.attr('y', 10)
		.attr('class', 'label')
		.text('Sepal Width');

svg.append('text')
		.attr('x', width)
		.attr('y', height - 10)
		.attr('text-anchor', 'end')
		.attr('class', 'label')
		.text('Sepal Length');

svg.selectAll(".dot")
    .data(data)
  .enter().append("circle")
    .attr("class", "dot")
    .attr("r", function(d) { return r(d.petal_length); })
    .attr("cx", function(d) { return x(d.sepal_length); })
    .attr("cy", function(d) { return y(d.sepal_width); })
    .style("fill", function(d) { return color(d.species); })
    .on("mouseover", function(d){
		   tooltip.transition()
		   	.duration(0)
		   	.style("opacity", .9);
		   tooltip.html("Species:" + d.species)
		   	.style("left", (d3.event.pageX + 5) + "px")
		   	.style("top", (d3.event.pageY - 28) + "px");
		 })
		.on("mouseout", function(d){
			tooltip.transition()
				.duration(500)
				.style("opacity",0);
		});

var legend = svg.selectAll(".legend")
    .data(color.domain())
  .enter().append("g")
    .attr("class", "legend")
    .attr("transform", function(d, i) { return "translate(0," + i * 20 + ")"; });

legend.append("rect")
      .attr("x", width - 18)
      .attr("width", 18)
      .attr("height", 18)
      .style("fill", color);

legend.append("text")
      .attr("x", width - 24)
      .attr("y", 9)
      .attr("dy", ".35em")
      .style("text-anchor", "end")
      .text(function(d) { return d; });

// get the x and y values for least squares
  	var xSeries = data.map(function (d) { return parseFloat(d['sepal_length']); })
		var ySeries = data.map(function(d) { return parseFloat(d['sepal_width']); });
		
		var leastSquaresCoeff = leastSquares(xSeries, ySeries);
		
		// apply the reults of the least squares regression
		var x1 = xSeries[0];
		var y1 = leastSquaresCoeff[0] + leastSquaresCoeff[1];
		var x2 = xSeries[xSeries.length - 1];
		var y2 = leastSquaresCoeff[0] * xSeries.length + leastSquaresCoeff[1];
		var trendData = [[x1,y1,x2,y2]];
		
		var trendline = svg.selectAll(".trendline")
			.data(trendData);
			
		trendline.enter()
			.append("line")
			.attr("class", "trendline")
			.attr("x1", function(d) { return x(d[0]); })
			.attr("y1", function(d) { return y(d[1]); })
			.attr("x2", function(d) { return x(d[2]); })
			.attr("y2", function(d) { return y(d[3]); })
			.attr("stroke", "black")
			.attr("stroke-width", 1);
		
		// display equation on the chart
		svg.append("text")
			.text("eq: " + decimalFormat(leastSquaresCoeff[0]) + "x + " + 
				decimalFormat(leastSquaresCoeff[1]))
			.attr("class", "text-label")
			.attr("x", function(d) {return xScale(x2) - 60;})
			.attr("y", function(d) {return yScale(y2) - 30;});
		
		// display r-square on the chart
		svg.append("text")
			.text("r-sq: " + decimalFormat(leastSquaresCoeff[2]))
			.attr("class", "text-label")
			.attr("x", function(d) {return x(x2) - 60;})
			.attr("y", function(d) {return y(y2) - 10;});

});
	
	
  
</script>

Modified http://d3js.org/d3.v4.min.js to a secure url

https://d3js.org/d3.v4.min.js