Nature-in-code/epidemics.html at master · vivekkrishna/Nature-in-code · GitHub

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<!DOCTYPE html>
<html>
	<head>
		<script src="https://d3js.org/d3.v4.min.js" charset="utf-8"></script>
	</head>
	<body>
		<script>
			function draw_grid(data,colors) {
				var width = 600;
				var height = 600;
				var grid_length = data.length;

				var svg = d3.select('body').append('svg')
					  .attr('width', width)
					  .attr('height', height);

				var rw = Math.floor(width/grid_length);
				var rh = Math.floor(height/grid_length);

				var g = svg.selectAll('g')
						.data(data)
						.enter()
						.append('g')
						.attr('transform', function (d, i) {
						  return 'translate(0, ' + (width/grid_length) * i + ')';
						});

				g.selectAll('rect')
						.data(function (d) {
						  return d;
						})
						.enter()
						.append('rect')
						.attr('x', function (d, i) {
						  return (width/grid_length) * i;
						})
						.attr('width', rw)
						.attr('height', rh)
						.attr('class',function(d) {
						  return d;
						});
				if (!colors) {
					d3.selectAll(".A1A1").style("fill","#fff");
					d3.selectAll(".A1A2").style("fill","#2176c9");
					d3.selectAll(".A2A2").style("fill","#042029");
				}
				else {
					for (var i = 0; i < colors.length; i = i + 2) {
						d3.selectAll("."+colors[i]).style("fill",colors[i+1]);
					}
				}
			}

			function update_grid(data,colors){
				var grid_length = data.length;
				d3.select('svg').selectAll('g')
					.data(data)
					.selectAll('rect')
					.data(function (d) {
					  return d;
					})
					.attr('class',function(d) {
					  return d;
					});
				if (!colors) {
					d3.selectAll(".A1A1").style("fill","#fff");
					d3.selectAll(".A1A2").style("fill","#2176c9");
					d3.selectAll(".A2A2").style("fill","#042029");
				}
				else {
					for (var i = 0; i < colors.length; i = i + 2) {
						d3.selectAll("."+colors[i]).style("fill",colors[i+1]);
					}
				}
			}

			var gridlength=100;
			var grid=[];
			var temp_grid=[];
			var beta=0.05;
			var gamma=0.1;

			function get_random_int(min,max){
				return Math.floor(Math.random()*(max-min+1))+min;
			}

			function init_grid(){
				for(var i=0;i<gridlength;i++){
					grid[i]=[];
					for(var ii=0;ii<gridlength;ii++){
						grid[i][ii]="S";
					}
				}
				grid[get_random_int(0,gridlength-1)][get_random_int(0,gridlength-1)]="I";
			}

			init_grid();

			draw_grid(grid,["S","#dcdcdc","I","#c82605","R","#6fc401"]);

			function simulate_and_visualize(){
				run_time_step();
				update_grid(grid,["S","#dcdcdc","I","#c82605","R","#6fc401"]);
			}

			setInterval(simulate_and_visualize,50);


			function run_time_step(){
				for(var i=0;i<gridlength;i++){
					temp_grid[i]=[];
					for(var ii=0;ii<gridlength;ii++){
						temp_grid[i][ii]=grid[i][ii];
					}
				}
				for(var i=0;i<gridlength;i++){
					for(var ii=0;ii<gridlength;ii++){
						if(grid[i][ii]=="I"){
							expose_neighbors(i,ii);
							try_recovery(i,ii);
						}
					}
				}
				for(var i=0;i<gridlength;i++){
					for(var ii=0;ii<gridlength;ii++){
						grid[i][ii]=temp_grid[i][ii];
					}
				}
			}

			function expose_neighbors(i,ii){
				for(var n_i=i-1;n_i<=i+1;n_i++){
					for(var n_ii=ii-1;n_ii<=ii+1;n_ii++){
						if(i==n_i && ii==n_ii){
							continue;
						}
						if(Math.random()<0.01){
							var random_i=get_random_int(0,gridlength-1);
							var random_ii=get_random_int(0,gridlength-1);
							try_infection(random_i,random_ii);
						}else{
							try_infection(get_bounded_index(n_i),get_bounded_index(n_ii));
						}
					}
				}
			}


			function try_infection(i,ii){
				if(grid[i][ii]=="S"){
					if(Math.random()<beta){
						temp_grid[i][ii]="I";
					}
				}
			}

			function try_recovery(i,ii){
				if(grid[i][ii]=="I"){
					if(Math.random()<gamma){
						temp_grid[i][ii]="R";
					}
				}
			}

			function get_bounded_index(index){
				var bounded_index=index;
				if(index<0){
					bounded_index=index+gridlength;
				}
				if(index>=gridlength){
					bounded_index=index-gridlength;
				}
				return bounded_index;
			}


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