foo.py

import random

positions = [0, 1, 2, 3]

# Represents sequence ACTG
bases = {
  0: "A",
  1: "C",
  2: "T",
  3: "G"
}

# Represents energies at position n. Initialize it as empty dict
energies = {}

for pos in positions:
  energies[pos] = random.random() # assign an energy to position pos; currently just random
  print "position %4d - %s energy: %4.2f kcal/mol" % (pos, bases[pos], energies[pos])