new_contents: # Reads data.txt into NumPy array and saves the array in binary format.
  # It is memory efficient.
  
  # You can work with the saved array as follows:
  #    >>> from numpy import load, shape, average
  #    >>> D = load("data.npy")
  #    >>> shape(D)
  #    (7, 14645083)
  #    >>> average(D[2, :])
  #    1965.7348883489171
  #    >>> average(D[3, :])
  #    11.469809257683686
  
  from numpy import empty, array, save
  N = 14645083
  D = empty((7, N))
  f = open("data.txt")
  i = 0
  for line in f:
      if line.startswith("%"): continue
      D[:, i] = array([float(x) for x in line.split()])
      i += 1
      if i % 100000 == 0: print "%.3f%%" % (100. * i / N)
  print "Saving..."
  save("data.npy", D)
  print "Done."
  
subject: Add conversion utility