buttons = {
d3.select(graphic1.parentNode).append("button")
.style("position","absolute")
.style("top","300px")
.style("right","200px")
.text("Gas")
.on("click", () => {showPathsByColor("#7f7f7f")});
d3.select(graphic1.parentNode).append("button")
.style("position","absolute")
.style("top","280px")
.style("right","200px")
.text("Electricity Grid")
.on("click", () => {showPathsByColor("#e377c2")});
}