layout html

<!DOCTYPE html>
<head>
  <meta charset="utf-8">
  <script src="https://d3js.org/d3.v4.min.js"></script>
  <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>
</head>

<body>
  
  <div>
    <div id="chart1" style="width:40%;height:200px;display:inline-block"></div>
    <div id="chart2" style="width:40%;height:200px;display:inline-block"></div>
  </div>
  <script>
function create_scatterplot(el,datafile,var_x,var_y,var_r,size){
  var margin = {top: 20, right: 20, bottom: 30, left: 40},
    width = 300 - margin.left - margin.right,
    height = 300 - margin.top - margin.bottom;
  
  var svg = el.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 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);
  //Lorsque d3 construit un color scale, il y a un range et un domaine
  //on construit ici un range de 20 couleurs et les domaines sont automatiquement   //attribuées. color.domain() renverra la liste des domaines attriuées au range
  //on peut passer un tableau à couleur.domaine()
var symbols = d3.scaleOrdinal(d3.symbols);

// creates a generator for symbols
var symbol = d3.symbol().size(100);

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

d3.csv(datafile, 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');
  	
  // we use the ordinal scale symbols to generate symbols
  // such as d3.symbolCross, etc..
  // -> symbol.type(d3.symbolCross)()
    svg.selectAll(".symbol")
    .data(data)
 		.enter().append("path")
    .attr("class", "symbol")
    .attr("id",function(d,i){return "id_" +i})//attribuer un id égal à l'index 
    //.attr("class",function(d){return d.species})
    .attr("d", function(d, i) { return symbol.type(symbols(d.species))(); })
    .style("fill", function(d) { return color(d.species); })
    //Attribution des domaines, le mapping entre le domaine et le range se fait  			//lors du premier appel
    .attr("transform", function(d) { 
      return "translate(" + x(d.sepal_length) + "," + y(d.sepal_width) +")"; 
    });
  
  var legend = svg.selectAll(".legend")
    .data(color.domain())
  	.enter().append("g")
    .attr("class", "legend")
    .attr("transform", function(d, i) { return "translate(0," + i * 20 + ")"; });
var clicked=null;
  legend.append("path")
    .style("fill", function(d) { return color(d); })
    	.attr("d", function(d, i) { return symbol.type(symbols(d))(); })
	    .attr("transform", function(d, i) { 
    		return "translate(" + (width -10) + "," + 10 + ")"; 
  		})
  		.on("click", function(d) {
    	console.log("test " + d);
       d3.selectAll(".symbol").style("opacity",1)
       
       if (clicked !==d){
       d3.selectAll(".symbol")
       .filter(function(e){return e.species !== d})
       .transition().duration(500).style("opacity", "0");
       clicked=d;
       }
				else {
          clicked=null;
        }
        });
 
  legend.append("text")
      .attr("x", width - 24)
      .attr("y", 9)
      .attr("dy", ".35em")
      .style("text-anchor", "end")
      .text(function(d) { return d; });

});
}
    create_scatterplot(d3.select("#chart1"),"iris.csv");//,'iris.csv',var_x,var_y,var_r,size)
create_scatterplot(d3.select("#chart2"),"iris.csv");
  </script>
</body>

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