From Last Class

• In Python there is no difference between "string" and 'string'

• String concatination can be performed without the + operator:

  >>> "hello " 'world'
  'hello world'

Some basic data structures

• >>> import sys
  >>> mytuple = ( 5, 'five', sys.stdout)

• >>> mylist = [ 1, 2, 3, 4 ]

• dictionary (dict): collection of name, value pairs

  >>> mydict = { 'five': 5, 'two': 2, 'seven': 7 }

Data operations

• strings can be split into lists
• lists and tuples are sequence types and can be indexed and sliced
• dictionaries can be converted to lists of tuples

Count Words

• split input into list of words, add each word to a dictionary with the word as the key and the number of occurances is the value

Source

• wordlist.py

  #!/usr/bin/env python3
  
  def word_list(stream):
      mywords = []
      for line in stream:
          for word in line.split():
              mywords.append(word)
  
      return mywords
  
  if __name__ == '__main__':
      from sys import stdin
  
      print(word_list(stdin))

• pyfreq.py

  #!/usr/bin/env python3
  
  import wordlist as wl
  from sys import stdin,stdout
  
  words = {}
  
  for word in wl.word_list(stdin):
      try:
          words[word] += 1
      except KeyError:
          words[word] = 1
  
  for key in words:
      print("{0}: {1}".format(key, words[key]))

Homework

PyFreq Part 1