1  #!/usr/bin/env python3
       2  
       3  """
       4  Markov chain simulation of words or characters.
       5  """
       6  
       7  class ESC[4;38;5;81mMarkov:
       8      def __init__(self, histsize, choice):
       9          self.histsize = histsize
      10          self.choice = choice
      11          self.trans = {}
      12  
      13      def add(self, state, next):
      14          self.trans.setdefault(state, []).append(next)
      15  
      16      def put(self, seq):
      17          n = self.histsize
      18          add = self.add
      19          add(None, seq[:0])
      20          for i in range(len(seq)):
      21              add(seq[max(0, i-n):i], seq[i:i+1])
      22          add(seq[len(seq)-n:], None)
      23  
      24      def get(self):
      25          choice = self.choice
      26          trans = self.trans
      27          n = self.histsize
      28          seq = choice(trans[None])
      29          while True:
      30              subseq = seq[max(0, len(seq)-n):]
      31              options = trans[subseq]
      32              next = choice(options)
      33              if not next:
      34                  break
      35              seq += next
      36          return seq
      37  
      38  
      39  def test():
      40      import sys, random, getopt
      41      args = sys.argv[1:]
      42      try:
      43          opts, args = getopt.getopt(args, '0123456789cdwq')
      44      except getopt.error:
      45          print('Usage: %s [-#] [-cddqw] [file] ...' % sys.argv[0])
      46          print('Options:')
      47          print('-#: 1-digit history size (default 2)')
      48          print('-c: characters (default)')
      49          print('-w: words')
      50          print('-d: more debugging output')
      51          print('-q: no debugging output')
      52          print('Input files (default stdin) are split in paragraphs')
      53          print('separated blank lines and each paragraph is split')
      54          print('in words by whitespace, then reconcatenated with')
      55          print('exactly one space separating words.')
      56          print('Output consists of paragraphs separated by blank')
      57          print('lines, where lines are no longer than 72 characters.')
      58          sys.exit(2)
      59      histsize = 2
      60      do_words = False
      61      debug = 1
      62      for o, a in opts:
      63          if '-0' <= o <= '-9': histsize = int(o[1:])
      64          if o == '-c': do_words = False
      65          if o == '-d': debug += 1
      66          if o == '-q': debug = 0
      67          if o == '-w': do_words = True
      68      if not args:
      69          args = ['-']
      70  
      71      m = Markov(histsize, random.choice)
      72      try:
      73          for filename in args:
      74              if filename == '-':
      75                  f = sys.stdin
      76                  if f.isatty():
      77                      print('Sorry, need stdin from file')
      78                      continue
      79              else:
      80                  f = open(filename, 'r')
      81              with f:
      82                  if debug: print('processing', filename, '...')
      83                  text = f.read()
      84              paralist = text.split('\n\n')
      85              for para in paralist:
      86                  if debug > 1: print('feeding ...')
      87                  words = para.split()
      88                  if words:
      89                      if do_words:
      90                          data = tuple(words)
      91                      else:
      92                          data = ' '.join(words)
      93                      m.put(data)
      94      except KeyboardInterrupt:
      95          print('Interrupted -- continue with data read so far')
      96      if not m.trans:
      97          print('No valid input files')
      98          return
      99      if debug: print('done.')
     100  
     101      if debug > 1:
     102          for key in m.trans.keys():
     103              if key is None or len(key) < histsize:
     104                  print(repr(key), m.trans[key])
     105          if histsize == 0: print(repr(''), m.trans[''])
     106          print()
     107      while True:
     108          data = m.get()
     109          if do_words:
     110              words = data
     111          else:
     112              words = data.split()
     113          n = 0
     114          limit = 72
     115          for w in words:
     116              if n + len(w) > limit:
     117                  print()
     118                  n = 0
     119              print(w, end=' ')
     120              n += len(w) + 1
     121          print()
     122          print()
     123  
     124  if __name__ == "__main__":
     125      test()