...

		function draw(data) {
			svg.selectAll("circle")
				.data(data, function(x){return x.name})
				.enter()
				.append("circle")
				.attr("r", 10)
				.attr("cx", function(x){return xScale(x.weight)})
				.attr("cy", function(x){return yScale(x.height)})
				.style("fill", function(x){return x.colour})
		}

		...