iris scatter plot

<!DOCTYPE html>
<meta charset="utf-8">
<title>D3 Scatterplot with Regression Line</title>
<style>
.line {
    stroke: #E4002B;
    fill: none;
    stroke-width: 3;
}

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

.axis text {
    font-size: 10px;
    font-family: sans-serif;
}

.text-label {
    font-size: 10px;
    font-family: sans-serif;
}

.dot {
    stroke: #293b47;
    fill: #7A99AC
}
</style>

<body>
    <script src="//d3js.org/d3.v4.js"></script>
    <script>
  
function compute_reg(data) {
  // copier-coller éhonté de la fonction de https://bl.ocks.org/ctufts/298bfe4b11989960eeeecc9394e9f118
        var x = [];
        var y = [];
        var n = data.length;
        var x_mean = 0;
        var y_mean = 0;
        var term1 = 0;
        var term2 = 0;
        var noise_factor = 100;
        var noise = 0;
        // create x and y values
        for (var i = 0; i < n; i++) {
          	d = data[i];           
            x.push(+d.sepal_width); 
          	y.push(+d.sepal_length);
            x_mean += x[i] ;
            y_mean += y[i] ;
        }
        // calculate mean x and y
        x_mean /= data.length;
        y_mean /= data.length;

// calculate coefficients
        var xr = 0;
        var yr = 0;
        for (i = 0; i < x.length; i++) {
            xr = x[i] - x_mean;
            yr = y[i] - y_mean;
            term1 += xr * yr;
            term2 += xr * xr;

}
        var b1 = term1 / term2;
        var b0 = y_mean - (b1 * x_mean);
        // perform regression

yhat = [];
        // fit line using coeffs
        for (i = 0; i < x.length; i++) {
            yhat.push(b0 + (x[i] * b1));
        }

for (i = 0; i < y.length; i++) {
            data[i].yhat = yhat[i];
        }
        return (data);
    };
      
      
      var dataset = [];
      
d3.csv("iris.csv", function(data) {
	
	var data = compute_reg(data);
  dataset.push([data]);      
      
  data = compute_reg(data);
     
	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]);
	  x.domain(d3.extent(data, function(d) { return +d.sepal_width; }));
	  y.domain(d3.extent(data, function(d) { return +d.sepal_length; }));

var xAxis = d3.axisBottom()
	    .scale(x)

var yAxis = d3.axisLeft()
	    .scale(y)

var svg = d3.select("body").append("svg")
        .attr("width", width+ margin.left + margin.right)
        .attr("height", height + margin.bottom + margin.top)
        .append("g")   
	.attr("transform", "translate(" + margin.left + "," + margin.top + ")");

var line = d3.line()
        .x(function(d) {return x(+d.sepal_width);        })
        .y(function(d) {return y(+d.yhat); });

var triangle = d3.symbol()
    		.type(d3.symbolTriangle)
    		.size(30);

var diamond = d3.symbol()
    		.type(d3.symbolDiamond)
    		.size(30);

var cross = d3.symbol()
    		.type(d3.symbolCross)
    		.size(30);

svg.selectAll("path")
        .data(data)
        .enter()
        .append("path")
        .attr("d",diamond)
   /*		 .attr("d",function(d) {
           	if (d.species == 'setosa') {
            	return cross;
         	}
      			else if (d.species == 'versicolor') {
           	return diamond;
         	} 
      			else if (d.species == 'virginica') {
            	return triangle;
          	} 
   			 })
        */
    // ne fonctionne pas 
    		.attr('fill',function(d) {
           	if (d.species == 'setosa') {
            	return 'red';
          	}
      			else if (d.species == 'versicolor') {
            	return 'blue';
          	} 
      			else if (d.species == 'virginica') {
            	return 'yellow';
          	} 
   			 })
        .attr("transform", function(d) { return "translate(" + x(+d.sepal_width) + "," + y(+d.sepal_length) + ")"; });
  
  
  
  
    svg.append("path")
        .datum(data)
        .attr("class", "line")
        .attr("d", line);
  
  svg.append("g")
      .attr("class", "x axis")
      .attr("transform", "translate(0," + height + ")")
      .call(xAxis)
    .append("text")
      .attr("class", "label")
      .attr("x", width)
      .attr("y", -6)
      .style("text-anchor", "end")
      .text("Sepal Width (cm)");

svg.append("g")
      .attr("class", "y axis")
      .call(yAxis)
    .append("text")
      .attr("class", "label")
      .attr("transform", "rotate(-90)")
      .attr("y", 6)
      .attr("dy", ".71em")
      .style("text-anchor", "end")
      .text("Sepal Length (cm)")

});

</script>
</body>

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