pythonChallenge

codes for the interesting riddles from Python Challenge

02/07/2018 Wed

string mapping

• implement the string.maketrans

  import string
  a = 'abc'
  b = 'xyz'
  transtab = string.maketrans(a,b)
  
  s = 'abcbabcbcba'
  res s.translate(transtab)
  
  # the same as dict(zip(a,b))

char, string operations

• check if a char is alpha/letters

  s = 'adas21234fsadfavFDDSFGG'
  s[6].isalpha()  # return boolean
  s[0].isupper()  # return False
  s[0].islower()  # return True
  
  import string
  s[4] in string.letters # return boolean

Q3_equality

• regex

  import re
  s = file('Q3_data.txt').read()
  pattern_test = "[^A-Z][A-Z]{3}([a-z])[A-Z]{3}[^A-Z]"
  pattern_test = "[^A-Z][A-Z]{3}[a-z][A-Z]{3}[^A-Z]"
  
  # re.findall(parrern, str) returns a list of results
  res_test = re.findall(pattern_test, s)
  ## ['qIQNlQSLi', 'eOEKiVEYj', 'aZADnMCZq', 'bZUTkLYNg', 'uCNDeHSBj', 'kOIXdKBFh', 'dXJVlGZVm', 'gZAGiLQZx', 'vCJAsACFl', 'qKWGtIDCj']
  res = re.findall(pattern, s)
  ## ['l', 'i', 'n', 'k', 'e', 'd', 'l', 'i', 's', 't']
  
  return "".join(res)
  ## linkedlist

Q4_linkedlist_urllib

• use urllib to open and read url

  import urllib
  content = urllib.urlopen(url).read()
  # .read() returns the whole string in the url

Q5_peak

peak hell -> pickle(泡菜)

• pickle/cPickle is a fundamental, but powerful algorithm for serializing and de-serializing a Python object structure.

  import urllib
  import pickle
  import pprint
  
  data_file = urllib.urlopen(url)
  obj = pickle.load(data_file)
  ## return a obj which is a list (may contain lists)
  pprint.pprint(obj,None,4)       # level-view, 4 is the indent for a new level

Q6_channel

• zipfile is a module to deal with zip files, it has a function named zipfile.ZipFile(zipname), which returns the obj of a zipfile.
• we can access the inner files with obj.read(file_name)
• we can access the info of inner files with obj.getinfo(file_name).comment

  import zipfile
  zfile = zipfile.ZipFile("Q6_channel.zip")
  # returns the obj of a zipfile(can access in inner files with obj.read(file_name))