digraph {
	fontname="Helvetica,Arial,sans-serif"
	node [fontname="Helvetica,Arial,sans-serif"]
	edge [fontname="Helvetica,Arial,sans-serif"]
	node [shape=circle fillcolor="white:black" fontcolor="black"]
	subgraph cluster_1 {
		label = "Linear Angle Variations (white to black gradient)";
		node [style=filled]
		n9 [gradientangle=360 label="n9:360"]; 
		n8 [gradientangle=315 label="n8:315"];
		n7 [gradientangle=270 label="n7:270"];
		n6 [gradientangle=225 label="n6:225"];
		n5 [gradientangle=180 label="n5:180"];
		n4 [gradientangle=135 label="n4:135"]; 
		n3 [gradientangle=90  label="n3:90 "];
		n2 [gradientangle=45  label="n2:45 "];
		n1 [gradientangle=0   label="n1:0  "];
	}

	subgraph cluster_2 {
		label = "Radial Angle Variations (white to black gradient)";
		node [style=radial]
		n18 [gradientangle=360 label="n18:360"];
		n17 [gradientangle=315 label="n17:315"];
		n16 [gradientangle=270 label="n16:270"];
		n15 [gradientangle=225 label="n15:225"];
		n14 [gradientangle=180 label="n14:180"];
		n13 [gradientangle=135 label="n13:135"];
		n12 [gradientangle=90  label="n12:90 "];
		n11 [gradientangle=45  label="n11:45 "];
		n10 [gradientangle=0   label="n10:0  "];
	}
    n5 -> n14;
}