bit manipulation frustration

[Peter Schneider-Kamp]

Courageous wrote:
> 
> First, in one fell swoop of antigenious, I seem to have
> forgotten how to convert strings to sequences of char and
> vice versa. Eeek. Help? Will someone please remind me and
> hit me with a rubber mallet??? :)

>>> map(None, "hello courageous")
['h', 'e', 'l', 'l', 'o', ' ', 'c', 'o', 'u', 'r', 'a', 'g', 'e', 'o',
'u', 's']
>>>

But what do you need this for? You can work on a string
like on that list except that the list is mutable.

I am not sure if I have understood your other problem though.
Maybe the following class can help you?

from operator import add

class isotile:
  def __init__(self, name, size, inc = 2):
    self.up = 1
    self.pos = 0
    self.num = inc
    self.size = size
    self.inc = inc
    self.data = open(name, "rb").read()
  def readline(self):
    if not self.num:
      return ''
    newpos = self.pos + self.num
    pad = (self.size - self.num) / 2
    line = self.data[self.pos:newpos]
    self.pos = newpos
    if self.up:
      if self.num == self.size:
        self.up = 0
        self.num = self.num - self.inc
      else:
        self.num = self.num + self.inc
    else:
        self.num = self.num - self.inc
    return pad * '\000' + line + pad * '\000'
  def readlines(self):
    result = [self.readline()]
    while result[-1]:
      result.append(self.readline())
    return result[:-1]
  def read(self):
    return reduce(add, self.readlines())

if __name__ == "__main__":
  open("isotile_test.dat","wb").write('112222333333444455')
  a = isotile("isotile_test.dat", 6)
  print a.readlines()
--
Peter Schneider-Kamp          ++47-7388-7331
Herman Krags veg 51-11        mailto:peter at schneider-kamp.de
N-7050 Trondheim              http://schneider-kamp.de