Random number proportional to its value.

gistfile1.py

def prop_random(r):
  S = sum(r)
  i = -1
  rand = random.randint(1,S)
  while(rand > 0):
    i = i + 1
    rand = rand - r[i]

  return r[i]

mm = dict() # Stores simulation results

N = 100000
for i in range(N):
  o = prop_random([5,2,1,4,3])
  if(o in mm):
    mm[o] += 1
  else:
    mm[o] = 1

for a,b in mm.iteritems():
  print a, " --> ", b/float(N)