OMG

from random import random, randrange

# SVG strings
# -----------

SVG_HEADER = '<svg xmlns="http://www.w3.org/2000/svg" width="%f" height="%f">'
SVG_LINE = '<path d="M %f,%f L %f,%f" style="stroke:black; stroke-width:%f; fill:none;" />'
SVG_CIRCLE = '<circle cx="%f" cy="%f" r="%f" style="fill:black; stroke:white; stroke-width:1px;" />'
SVG_FOOTER = '</svg>'


# Initial settings and data
# -------------------------

graph_width = gw = 500
graph_height = gh = 500
line_width = 1
circle_radius = cr = 10
circle_diameter = cd = 2 * circle_radius

nodes_count = nc = 100
edges_count = ec = 500

rndw = lambda: (graph_width - cd) * random() + cr
rndh = lambda: (graph_height - cd) * random() + cr

random_nodes = [(rndw(),rndh()) for _ in range(nodes_count)]
random_edges = [(randrange(nc),randrange(nc)) for _ in range(edges_count)]


# The Program
# -----------

print(SVG_HEADER % (graph_width, graph_height))

for e1,e2 in random_edges:
    x1, y1 = random_nodes[e1]
    x2, y2 = random_nodes[e2]
    print(SVG_LINE % (x1, y1, x2, y2, line_width))

for x, y in random_nodes:
    print(SVG_CIRCLE % (x, y, circle_radius))

print(SVG_FOOTER)

# End.