How to learn Python in a 15 Minutes !! Believe its very cool language to have fun and learn :)

How to learn Python in a 15 Minutes !! Believe its very cool language to have fun and learn .py

#!/usr/bin/env python

# I have learned these codes from Learning Python O'reilly
# Python 2.7

"""

    #! is often called hash bang or shebang 
    /user/bin/python - path of the python executable
    #!/usr/bin/python - Unix Styled Executable Scripts (If u know exact path of the python binary)
    #!/usr/bin/env python - No matter python lives on your system

"""


def about_python():
    """
    @desc Some facts about the python
    """
    interesting_python = """
                    Few Interesting facts about the Python
                    =================================================================================================
                    [*] The Standard implementation of Python is written in portable ANSI C
                        (Python code runs close to C speed anyhow that involves C code in the interpreter)
                    [*] Written By Guido Van Rossum
                        (Python named after comedy series 'Monty Python's Flying Circus')
                    [*] Python is the Object-Oriented Scripting Language.(Python sees the everything as a object)
                    [*] Python is a general purpose programming language that blends procedural (statement-based),
                        functional and object-oriented (class-based) paradigms
                    [*] Top Down Approach - step by step control flow
                    [*] Python Source code is compiled to the intermediate format called 'Byte Code' (using interpreter)
                        then routed to 'Python Virtual Machine' (PVM) runtime engine of python

                        --------------------------------------------------------------
                        | Python(.py) --> Byte Code (.pyc) --> Python Virtual Machine |
                        --------------------------------------------------------------

                    [*] Byte Code (Low level ) provides the portability, as it a platform independent
                    [*] Python code must always be run by this interpreter
                    [*] Python's standard library comes with POSIX bindings and support for all Operating Systems
                        (Portable Operating Systems Executable)
                    [*] Apart from the polymorphism, operator overloading and multiple inheritance
                        Python includes generators, comprehensions, closures, maps, decorators, anonymous functions
                        lambdas and first class functions objects

                    [*] PowerFul tool, Mixable and relatively easy to use
                        [+] Dynamic Typing (auto types identification)
                        [+] Automatic Memory Management
                        [+] Programming in the large support
                        [+] Built-in Object types
                        [+] Built-in tools
                        [+] Library utilities
                        [+] 3rd party utilities
                    """

    print interesting_python

    company_uses_python = """
                      Famous Company or Organization that uses Python Today
                      =================================================================
                      [*] Google
                      [*] DropBox
                      [*] Raspberry Pi
                      [*] Google App Engine
                      [*] Maya
                      [*] NASA (Cryptography and Intelligence)
                      [*] Bit Torrent
                      [*] Intel, Cisco, HP, Seagate and Qualcomm (Hardware testing)
                      [*] JP Morgan
                         """

    print company_uses_python, '\n'

    python_concepts = """
                    The Python Conceptual Hierarchy
                    ================================================================
                    In python, data takes the form of objects. Everything is an object in a python script.
                    Objects are the most fundamental notion in python programming.

                    Python can be decomposed into modules, statements, expressions and object as follows:
                    1. Programs are composed of modules
                    2. Modules contain statements
                    3. Statements contain expressions
                    4. Expressions create and process objects

                    ---------------------------------------------------------------------------------
                    | program -> modules -> statements -> expressions -> create and process objects |
                    ---------------------------------------------------------------------------------
                    """

    print python_concepts, '\n'

    python_data_types = """
                    Object Type                 Examples literals/creation
                    ===========================================================================
                    Number              1234, 3.145, 3+4j, 0b111, Decimal(), fraction()
                    Strings             'spam', Bob's", b'a\x01c', u'sp\xc4m'
                    Lists               [1, [2, 'three'], 4.5], list(range(10))
                    Dictionaries        {'food': 'spam', 'taste': 'yum'}
                    Tuples              tuple('spam'), ('1', 'spam', 4, 'U')
                    Files               open('eggs.txt'), open(r'C:\ham.bin', 'wb')
                    Sets                set('abc')
                    Other core types    Boolean, types, None
                    Program unit types  Functions, modules, classes
                    Implementation      Compiled code, stack tracebacks
                    related types
                        """
    print python_data_types, '\n'

# In-built commands or options


def printing_comments():
    """
    @desc This function shows the different methods for printing the values
    """
    about = "\nprint and comments \n================================="
    print about

    '''
    Multiple Line Comments
    You can type your function description or anything you want
    '''
    print 'Hello World!'
    print('Printing the string as a calling function')
    print(2**8)
    print 'Spam!' * 8  # Single line  Comments can be given here

    x = 'Py'
    print(x*8)

    print '%s, eggs and %s' % ('Spam', 'SPAM!')
    print '{}, eggs and {} '.format('Spam', "SPAM!")
    print '{0}, eggs and {1}'.format('Spam', 'SPAM!')

    print '{:,.2f}'.format(296999.23674)

    print '%.2f | %+05d' % (3.14159, -42)
    run_time_value = raw_input("Enter some value here : ")  # Use input() in python 3.x
    print "You have entered, ", run_time_value

    try:
        import os
        executable_value = input("Enter vulnerable value here : ")
        # Don't use input() is vulnerable functions as it execute the commands directly without any input validation
        # Example: enter os.getcwd()
        print "You have entered, ", executable_value
    except Exception as error:
        print "Error: ", str(error)


def use_of_imports():
    about = "\n importing modules \n=============================================="
    print about
    import os
    print "os.getcwd() --> ", os.getcwd()

    from os import getcwd   # Directly calling the function
    # from myfile import title is not recommended
    # as the namespace replace the other functions names without any warnings
    from imp import reload  # Used to reload the module namespaces
    reload(os)
    print "getcwd() --> ", getcwd()

    vijay = 'Wait for the myscript1 module'
    file_path ='/not/a/correct/path/'

    print "Vijay = ", vijay

    print 'Loading the value from myscript1.py'
    with open("myscript1.py", 'w+') as file:
        file.write("#!/usr/bin/python \n")
        file.write("import os \n")
        file.write('''file_path = os.getcwd(); \n''')
        file.write('''vijay = "My Name is Vijay Anand"''')
    file.close()

    exec(open('myscript1.py').read())   # Another Method loading the module the program
    print "Look here now -->>> ", vijay
    print "File_path -->>> ", file_path


def help_option():
    about = "\n Help Options \n=============================================="
    print about
    import sys
    print "Directory Options", dir(sys), '\n'
    print "List of options for sys.path, ", dir(sys.path)
    print "Usage of sys.path :  ", help(sys.path)


def for_loop():
    about = "\n for loop conditions \n=============================================="
    print about
    for x in 'spam':
        print x


def python_numbers():
    about = "\n Python Number Data types  \n=============================================="
    print about
    print '123 + 222 = ', 123 + 222, type(123 + 222)
    temp = 1.5 * 25
    print '1.5 * 25 = ', temp, type(temp)
    print '2 * 100 = ', 2 ** 100
    print 'len(str(2 ** 1000000)) = ', len(str(2 ** 1000000))


def python_strings():
    about = "\n Python String Data types  \n=============================================="
    print about
    S = 'Spam!'
    print S[0]
    print S[1]
    print "Reverse of the String, ", S[::-1]
    print(S[-2])
    print S[:]     # String slicing concept in python
    print S[1:3]
    print S[:3]
    print S[1:]
    print len(S)
    print S + 'xyz'
    print S * 8
    S = 'Z' + S[1:]  # Concatenation
    print S
    S = 'nobody cares nobody'
    print S
    L = list(S)
    print L
    L = list('every') + L[2:]
    print ''.join(L)

    B = bytearray('spam')
    B.extend('eggs!')
    print 'ByteArray = ', B
    print B.decode()

    S = 'SpamSpam'
    print S.find('pam')
    print S.replace('pa', 'ABCD')
    print S.upper()
    print S.lower()
    print S.isalpha()

    line = 'aaa,bbb,ccc,ddd'
    print line.split(',')
    line = 'aaa,bbb,ccc,dd\n\t'
    print line.rstrip()

    S = 'A\nB\tC'
    print len(S)
    print "ord(\\n) = ", ord('\n')  # \n  byte with binary value 10 in ASCII

    S = 'A\0B\0C'
    print len(S), S

    print 'spam'.encode('utf8')
    print 'spam'.encode('utf16').decode('utf16')


def python_lists():
    about = "\n Python List Data types  \n=============================================="
    print about
    L = [123, 'spam', 1.23]
    print len(L)
    print L[0]
    print L[:-1]
    L = L + [4, 5, 6]
    L.reverse()
    print 'Reverse: ', L
    L.sort()
    print 'Sort = ', L
    print L * 2
    L.append('NI')
    print L
    L.pop(4)  # Pop the 4th element
    print L
    print L[::-1]


def python_comprehensions():
    about = "\n Python Comprehension Data types  \n=============================================="
    print about
    M = [[1, 2, 3],
         [4, 5, 6],
         [7, 8, 9]]

    print M
    print M[1][2]

    for row in M:
        print row

    col2 = [row[1] for row in M]
    print col2, '\n'

    col3 = [row[1] + 1 for row in M]
    print col3

    print [row[1] for row in M if row[1] % 2 == 0]

    diagonal_matrix = [M[i][i] for i in [0, 1, 2]]
    print 'Diagonal Matrix = ', diagonal_matrix

    doubles = [c * 2 for c in 'spam']
    print 'Doubles = ', doubles

    print list(range(10))
    print list(range(-6, 7, 2))
    print [[x**2, x**3] for x in range(4)]
    print [[x, x/2, x*x] for x in range(-6, 7, 2) if x > 0]

    G = (sum(row) for row in M)  # Generator
    print next(G)
    print next(G)
    print next(G)
    # print next(G) Throws an error

    print list(map(sum, M))     # Function Mapping

    print {sum(row) for row in M}
    print {i: sum(M[i]) for i in range(3)}

    print [ord(x) for x in 'VijayAnand']
    print {ord(x) for x in 'VijayAnand'}
    print {x: ord(x) for x in 'VijayAnand'}


def python_dict():
    about = "\n Python Dictionary Data types  \n=============================================="
    print about

    D = {'food': 'Noodles', 'quantity': 4, 'color': 'pink'}
    print D['food']

    D['quantity'] += 1
    print D

    # Method 1 for creating dictionary
    D = {}
    D['name'] = 'Bob'
    D['job'] = 'dev'
    D['age'] = 40
    print D

    # Method 2 for creating dictionary
    bob1 = dict(name='Bob', age=40, job='dev')
    print bob1

    # Method 3 for creating dictionary
    bob2 = dict(zip(['name', 'age', 'job'], ['Bob', 40, 'dev']))
    print bob2

    # Nested Dictionaries
    rec = {'name': {'first': 'Bob', 'last': 'Smith'},
           'jobs': ['dev', 'mgr'],
           'age': 40.5}

    print rec['name']
    print "Last Name  is %s " % (rec['name']['last'])

    print rec['jobs']
    rec['jobs'].append('CEO')
    print rec['jobs']
    print rec['jobs'][-1]

def python_tuples():
    about = "\n Python Tuples Data types  \n=============================================="
    print about

    T = (1, 2, 3, 4)
    print len(T)
    T = T + (5, 6)
    print T

    print T.index(5)
    print T.count(4)

    T = 'spam', 3.0, [11, 22, 33]

    print T


# Library or Modules


def lib_math():
    about = "\n math module \n=============================================="
    print about
    try:
        import math
        print "Importing Math module"
    except ImportError, error:
        print "Error: ", str(error)
        return -1

    print math.pi
    print math.sqrt(85)


def lib_random():
    about = "\n random module \n=============================================="
    print about
    try:
        import random
        print "Importing random module"
    except ImportError, error:
        print "Error: ", str(error)

    print random.random()
    print random.randint(25, 35)
    print random.choice([1, 2, 3, 4])


def lib_os():
    about = "\n os (Operating System) module \n=============================================="
    print about

    import os
    print "Current Working directory ", os.getcwd()

    print "To execute the commands in operating system  os.system()"
    os.system("type chmod")
    # type is used to locate the path of the builtin options binary in terminal


def lib_sys():
    about = "\n sys (System) module \n=================================================="
    print about

    import sys
    print("Your Operating System is "+sys.platform)


def main():
    about_python()
    printing_comments()
    use_of_imports()
    help_option()
    python_numbers()
    python_strings()
    python_lists()
    python_comprehensions()
    python_dict()
    python_tuples()
    for_loop()
    lib_math()
    lib_random()
    lib_os()
    lib_sys()

if __name__ == '__main__':
    try:
        main()
    except Exception, er:
        print "Error: ", str(er)