-----------------
Librairies utiles
-----------------

Module os
----------

    >>> import os
    >>> os.getcwd()
    '/Users/laurentpaoletti/Documents/WRK/PRJ/Cours python ISEN/Seance 2'


    >>> os.listdir(os.curdir)
    ['.DS_Store', 'classes.rst', 'libraries.rst', 'myui.py', 'myui.pyc', 'myui.ui', 'pyside.rst', 'pyside1.py', 'pysid
    e2.py', 'pyside3.py', 'pyside4.py', 'pyside_creator.py', 'tk1.Py', 'tk2.Py', 'tk3.py', 'tk4.py', 'tk5.py', 'tk6.py
    ', 'tk7.py', 'tkinter.rst']


    >>> os.name
    'posix'

Pathname manipulation
----------------------

    >>> print (os.path.join('path' ,'to', 'my', 'dir'))
    path/to/my/dir

    >>> os.path.exists('/Users/me/file.txt')
    True
    >>> os.path.isdir('/Users/me/')
    True
    >>> os.path.isfile('/Users/me/file.txt')
    True

Parcourir une arborescence
---------------------------
    >>> for root, dirs, files in os.walk(os.curdir):
    ...     print("{0} has {1} files".format(root, len(files)))


Fichiers
--------
Ouvrir un fichier

::

    >>> file_object = open('myfile', 'r') #en lecture
    >>> line = file_object.readline()

Mode d'ouverture

- w overwrite
- a ajout
- w+ lecture ecriture, overwrite
- a+ lecture ecriture, ajout

fermer un fichier

::

    >>> file_object.close()

Ouvrir en ecriture

::

    >>> file_object = open("myfile", 'w') #en ecriture
    >>> file_object.write(“Hello, World\n”) 
    >>> file_object.close()

Lire un fichier

::

    >>> file_object = open("myfile", 'r') 
    >>> count = 0
    >>> while file_object.readline() != "":
    >>> count = count + 1 print(count)
    >>> file_object.close()

Avec un context manager

::

    >>> with open('workfile', 'r') as f:
    ...     read_data = f.read()

Ecrire des lignes à la suite

::

    >>> file_object = open("hello.txt", "w")
    >>> lines_of_text = ["a line of text", "another line of text", "a third line"]
    >>> file_object.writelines(lines_of_text)

Cryptographie
------------

::

    >>> import hashlib
    >>> data = "Lorem ipsum dolor sit amet, consectetur adipisicing elit"
    >>> h = hashlib.md5()
    >>> h.update(data)
    >>> h.hexdigest()
    '1a16b08270f1994e35ee1d6a42478f13'
    >>> h2 = hashlib.sha1()
    >>> h2.update(data)
    >>> h2.hexdigest()
    'b71d554ddfdf8e6a2518b4eacc93dcb06952ee5e'

Mathematics
-----------

::

    >>> import math
    >>> math.sin(0)
    0.0
    >>> math.sin(math.radians(90))
    1.0

random
-------

    >>> import random
    >>> random.randint(1, 100)
    87

random système (mieux)

    >>> r =  random.SystemRandom()
    >>> r.random()
    0.4599472067935497

Pickle
------

Attention: sécurité

Ecriture


::

    >>> import pickle
    >>> file = open("state", 'w') 
    >>> pickle.dump(a, file) 
    >>> pickle.dump(b, file) 
    >>> pickle.dump(c, file) 
    >>> file.close()

Lecture

::

    >>> import pickle
    >>> file = open('pickled', 'r')
    >>> a = pickle.load(file)
    >>> a
    'foo'