>>> a = 123     # integer
>>> b = -178    # negative integer 
>>> c = 0 
>>> print a, b, c
123 -178 0
>>> print type(a), type(b), (c)   # in python 3.0 type -> class
<type 'int'> <type 'int'> 0
>>> a = 1.2     # float-point
>>> b = -3.45
>>> c = 4.24E10
>>> d = 4.24e-10
>>> print a, b, c, d
1.2 -3.45 42400000000.0 4.24e-10
>>> print type(a), type(b), type(c), tyep(d)
<type 'float'> <type 'float'> <type 'float'>
>>> print type(a), type(b), type(c), type(d)
<type 'float'> <type 'float'> <type 'float'> <type 'float'>
>>> a = 0o177    # octal numeric
>>> a
127
>>> b = 0x8ff    # hexa numeric
>>> b
2303
>>> a = 3       # calculation with '+, -, *, /, // %'
>>> b = 4
>>> a + b
7
>>> a - c
-42399999997.0
>>> a - b
-1
>>> a * b
12
>>> a / b     # in python 3.0, 0 -> 0.75 
0
>>> a // b    # '//' operator is similar to floor function of math
0
>>> a ** b
81
>>> a % b
3

>>> str = "Life is too short, you need to learn python"
>>> print str
Life is too short, you need to learn python
>>> print type(str)                                   # in python 3.0, type -> class
<type 'str'>
>>> str = 'Life is too short, you need to learn python'
>>> print str
Life is too short, you need to learn python
>>> print type(str)
<type 'str'> 
>>> str = """                             # for multilines with '''string''', 'string \n string', another way is with """string""" and "string \n string"
... Life is too short, 
... you need to learn Python
... """
>>> print str

Life is too short, 
you need to learn Python

>>> print type(str)
<type 'str'>
>>> say = '"Python is very easy to learn" I said'           # how to use ' and " together
>>> print say
"Python is very easy to learn" I said
>>> print type(say)
<type 'str'>
>>> say = "'Python is very easy to learn' I said"
>>> print say
'Python is very easy to learn' I said
>>> print type(say)
<type 'str'>
>>> say = "\"Python is very easy to learn\" I said"
>>> print say
"Python is very easy to learn" I said
>>> print type(say)
<type 'str'>


>>> head = "python "                      # extension of string
>>> tail = "looks like fun"
>>> head + tail
'python looks like fun'
>>> head * 3
'python python python '
>>> str = "Life is too short, you need to learn python"           # indexing and slicing of string
>>> str[3]
'e'
>>> str[:3]
'Lif'
>>> str[3:]
'e is too short, you need to learn python'
>>> str[-1]
'n'
>>> str[8:-1]
'too short, you need to learn pytho'
>>> str1 = "20170405sunny"
>>> year = str1[0:4]
>>> date = str1[4:8]
>>> weather = str1[8:]
>>> year
'2017'
>>> date
'0405'
>>> weather
'sunny'
>>> test =  "pithon"                    # string is immutable, So you have to create new string when you fix string, wrong letter.
>>> test[1] = y
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'str' object does not support item assignment
>>> test = test[0] + "y" + test[2:]
>>> test
'python'

>>> number = 10                         # string formatting 
>>> day = "three"
>>> "After I ate %d apples, I was sick for %s days" % (number, day)
'After I ate 10 apples, I was sick for three days'

>>> "Error is %d%%" % 10                # %%
'Error is 10%'
>>> "%10s" % "hi"
'        hi'
>>> "%-10s" % "hi"
'hi        '
>>> "%-10s Let's study python" % "hi"
"hi         Let's study python"
>>> "%0.4f" % 3.124567
'3.1246'
>>> "%10.4f" % 3.124567
'    3.1246'
>>> "%-10.4f" % 3.124567
'3.1246    '

>>> str = "python is the best language in the world to learn fast"   # string object method
>>> str.count('i')
2
>>> str.find('i')
7
>>> str.find('0')
-1
>>> str.index('0')                                  # error happens when you search for something out of the original string. taht is how different between find() and index()
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: substring not found
>>> str.index('i')
7
>>> str1 = "."
>>> str1.join("ASAP")
'A.S.A.P'
>>> str.upper()                                               # upper case and lower case
'PYTHON IS THE BEST LANGUAGE IN THE WORLD TO LEARN FAST'
>>> str.lower()
'python is the best language in the world to learn fast'
>>> str2 = " test "
>>> str2.lstrip                                             # strip function, how to eliminate the blank of the string
<built-in method lstrip of str object at 0x141bf00>
>>> str2.lstrip()
'test '
>>> str2.rstrip()
' test'
>>> str2.strip()
'test'
>>> str2.replace("test", "python")                      # How to replace the old one with the new one
' python '
>>> str.split()                                         # how to split string into list
['python', 'is', 'the', 'best', 'language', 'in', 'the', 'world', 'to', 'learn', 'fast']
>>> str3 = "A.S.A.P"
>>> str3.split(".")
['A', 'S', 'A', 'P']

>>> "After I ate {0} apples. I was sick for {days} days".format(10,days=7)        # in here, further advance of formatting with format function 
'After I ate 10 apples. I was sick for 7 days'
>>> "{0:>10}".format("hi")
'        hi'
>>> "{0:<10}".format("hi")
'hi        '
>>> "{0:^10}".format("hi")
'    hi    '
>>> "{0:=^10}".format("hi")
'====hi===='
>>> "{0:=>10}".format("hi")
'========hi'
>>> "{0:=<10}".format("hi")
'hi========'
>>> y=3.1245497
>>> "{0:0.4f}".format(y)
'3.1245'
>>> "{0:10.4f}".format(y)
'    3.1245'
>>> "".format()
'{ and }'

python 2.7 - print "stirng"
python 3.6 - print ("String")

>>> a = [1, 2, 3]
>>> print (type(a))     ## Prints "<class 'list'>"
>>> print (type(3))     ## Prints "<class 'int'>"

>>> "let's do python tutorial"
"let's do python tutorial"
>>> a = []
>>> b = [1,2,3]
>>> c = ['Life', 'is', 'too', 'fun']
>>> d = [1, 2, 'Life', 'fun', 'is']
>>> e = [1, 2, ['Life', 'is']]
>>> e = [[1, 2], ['Life', 'is']]
>>> e = [1, 2, ['Life', 'is']]
>>> f = [[1, 2], ['Life', 'is']]               # idexing of list
>>> e[0]
1
>>> e[1]
2
>>> e[2]
['Life', 'is']
>>> e[2][1]
'is'
>>> f[0][1]
2
>>> f[1]
['Life', 'is']
>>> f[-1][1]
'is'
>>> b + c
[1, 2, 3, 'Life', 'is', 'too', 'fun']
>>> a + b + c + d + e + f
[1, 2, 3, 'Life', 'is', 'too', 'fun', 1, 2, 'Life', 'fun', 'is', 1, 2, ['Life', 'is'], [1, 2], ['Life', 'is']]
>>> a = [1, 2, ['a', 'b', ['Life', 'is']]]
>>> a[2][2][0]
'Life'
>>> a = [1,2,3,4,5]      # the span to slice list - is the same from string. 
>>> b = "12345"
>>> a[:3]
[1, 2, 3]
>>> b[:3]
'123'
>>> a = [1, 2, ['a', 'b', ['Life', 'is']]]
>>> a[2][:2]
['a', 'b']

>>> a = [1, 2, 3]
>>> b = [4, 5, 6]
>>> a + b
[1, 2, 3, 4, 5, 6]
>>> a * 3
[1, 2, 3, 1, 2, 3, 1, 2, 3]
>>> a ** 3
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unsupported operand type(s) for ** or pow(): 'list' and 'int'
>>> a + "hi"
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: can only concatenate list (not "str") to list
>>> a  =  [1, 2, 3]
>>> a[2] = 4
>>> a
[1, 2, 4]
>>> a[1:2]
[2]
>>> a[1:2] = ['a', 'b', 'c']
>>> a
[1, 'a', 'b', 'c', 4]
>>> b = [1, 2, 3]
>>> b[2] = ['a', 'b', 'c']
>>> b
[1, 2, ['a', 'b', 'c']]
>>> a[1:3] = []        ## how to erase list with none object !
>>> a
[1, 'c', 4]
>>> del a[1]           ## python del function, this fucntio usage is 'del object'!!
>>> a
[1, 4]
>>> del a[0:]
>>> a
[]
>>> a = [1, 4, 2]
>>> a.sort()
>>> a
[1, 2, 4]
>>> a.append(2)         ## just literally, append a factor in last location. BUT, insert is you can make where you want to place factor in the list
>>> a
[1, 2, 4, 2]
>>> a = ['c', 'a', 'e']
>>> a.sort()            ## sorting fucntion alphabetically, numerically like increment way BUT, 
>>> a = [1, 4, 2, 'a', 'o', 'e']
>>> a.sort()            ## keep in mind, you need to compare the same type.
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: '<' not supported between instances of 'str' and 'int'
>>> a
['a', 'c', 'e']
>>> a.reverse()         ## In case you want to reverse the list 
>>> a
['e', 'c', 'a']
>>> a.index('c')         ## When you want to look up the index number of factor that you'r looking for  
1
>>> a.index(0)           ## when you search for no factor in list  
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: 0 is not in list
>>> a.insert(1, 3)        ## When you want to insert the particular factor into list, BUT, you will have to declare loction to inser. 
>>> a
['e', 3, 'c', 'a']
>>> a.remove(3)           ## if you want to remove the particular factor in list
>>> a
['e', 'c', 'a']
>>> a.remove(3)           ## if you remove fator is no there
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
ValueError: list.remove(x): x not in list
>>> a = [1, 2, 3]
>>> a.pop()               ## To pop the last factor of list like Stack function of pop ()
3
>>> a
[1, 2]
>>> a.extend([4,5,6,7])   ## To extend a list with [4, 5, 6, 7] it's like **a += [4, 5, 6, 7]** and **a = a + [4, 5, 6, 7] **
>>> a
[1, 2, 4, 5, 6, 7]
>>> a.pop(2)              ## To pop the particular location's factor of list like Stack function of pop ()
4
>>> a
[1, 2, 5, 6, 7]
>>> a.append(2)
>>> a
[1, 2, 5, 6, 7, 2]        ## how many factors of the particular factor like '2' is in list ? 
>>> a.count(2)
2

>>> t1 = ()
>>> t2 = (1,)                ## you need char '(' and ')' when you make Tuple. 
>>> t2                      
(1,)
>>> print (type(t2))         ## Prints "<class 'tuple'>"
>>> t2 = (1)
>>> t2
1
>>> print (type(t2))        ## Prints "<class 'int'>"
>>> t2 = (1,)               ## i.e, If you tuple with one factor, you have to use '(' and ')'
>>> t2 = (1, 2, 3)
>>> t3 = 1, 2, 3
>>> t4 = ('a', 'b', ('ab', 'cd'))
>>> t5 = (1, (2,3), ('a', 'b'), 'c')
>>> t5
(1, (2, 3), ('a', 'b'), 'c')
>>> t5 = (1, (2,3), ('a', 'b'), 'c',1)
>>> t5
(1, (2, 3), ('a', 'b'), 'c', 1)
>>> t2
(1, 2, 3)
>>> t2[1]
2
>>> del t2[1]                ## when you remove factor from  tuple, error happens
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'tuple' object doesn't support item deletion
>>> t2[1]  = 'a'
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'tuple' object does not support item assignment
>>> t2[1:2]  = 'a'
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'tuple' object does not support item assignment
>>>

>>> t1 = (1, 2, 'a', 'b')
>>> t1[0]
1
>>> t1[0:]
(1, 2, 'a', 'b')
>>> t1[0:3]
(1, 2, 'a')
>>> t2 = (3, 4)
>>> t1 + t2
(1, 2, 'a', 'b', 3, 4)
>>> t2 * 3
(3, 4, 3, 4, 3, 4)
>>> t1 * 2
(1, 2, 'a', 'b', 1, 2, 'a', 'b')

>>> dic = {'name': 'hyunyoung2', 'phone':'00011112222', 'birth':'1111' }   ## how to make dictionary
>>> dic
{'name': 'hyunyoung2', 'phone': '00011112222', 'birth': '1111'}
>>> print (type(dic))          ## Prints "<class 'dict'>"
>>> a = {1: 'hello world'}
>>> a[1]
'hello world'
>>> a = {'a': [1,2,3]}
>>> a['a']
[1, 2, 3]

>>> a = {1: 'a'}            ## from now on, How to insert factor into Dictionary
>>> a[2] = 'b'
>>> a
{1: 'a', 2: 'b'}
>>> a = {1: 'a'}
>>> a
{1: 'a'}
>>> a[2] = 'b'
>>> a
{1: 'a', 2: 'b'}
>>> a['name'] = 3
>>> a[(1,2)] = [1,2,3]
>>> a[[1,2]] = [1,2,3]      ## you can use tuple, integer, string as look-up, but cannot use set, list Because unhashed type. 
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unhashable type: 'list'
>>> a[[1,2]] = 1
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unhashable type: 'list'
>>> a[{1,2}] = 1
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unhashable type: 'set'
>>> del a[1]
>>> a
{2: 'b', 'name': 3, (1, 2): [1, 2, 3]}
>>> del a['name']
>>> a
{2: 'b', (1, 2): [1, 2, 3]}

>>> a = {"name": "hyunyoung2", "Object":"To Study python", "Chapter":"Dictionary"}
>>> a
{'name': 'hyunyoung2', 'Object': 'To Study python', 'Chapter': 'Dictionary'}
>>> a.keys()                                    ## only to extract key value
dict_keys(['name', 'Object', 'Chapter'])
>>> for i in a.keys() :
...     print  (i)
...
name
Object
Chapter
>>> for i in a.values() :                       ## onle to extract value
...     print (i)
...
hyunyoung2
To Study python
Dictionary
>>> list(a.keys())
['name', 'Object', 'Chapter']
>>> list(a.values())
['hyunyoung2', 'To Study python', 'Dictionary']
>>> a.items()                                  ## a pair of key and value, it's similar to enumerate fucntion of list 
dict_items([('name', 'hyunyoung2'), ('Object', 'To Study python'), ('Chapter', 'Dictionary')])
>>> list(a.items())             
[('name', 'hyunyoung2'), ('Object', 'To Study python'), ('Chapter', 'Dictionary')]
>>> a.clear()
>>> a
{}
>>> a = {"name": "hyunyoung2", "Object":"To Study python", "Chapter":"Dictionary"}
>>> a.get('name')                               ## not indexing, just get function is used. 
'hyunyoung2'
>>> a.get('Object')
'To Study python'
>>> a.get('test')
>>> a.get('test', 'by default')
'by default'
>>> 'name' in a                                 ## "in" operator, a has 'name' in a Dictionary, this returns True(boolean value)
True
>>> 'test' in a                                 ## the opposite of the above situation
False

>>> a = set([1,2,3])          ## you can see how to intialize set, from now on. 
>>> a
{1, 2, 3}
>>> print (type(a))           ## Prints "<class 'set'>"
>>> b = set("hello")         ## over here, You can verify the features of the set of python's data type.  
>>> b                         ## First, There is no duplication,  one of two "l" letters disappear. 
{'l', 'o', 'e', 'h'}     ## Second, it's unodered.
>>> print (type(b))           ## Prints "<class 'set'>"
>>> c = {1,2,3,4, "hello"}    ## if you initialize a set this way, then "hello" is dealt with like one data. 
>>> c
{1, 2, 3, 4, 'hello'}
>>> print (type(c))           ## Prints "<class 'set'>"
>>> a[1]                      ## As you can see, you cannot index in the set. 
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'set' object does not support indexing

>>> a = set([1,2,3])
>>> a
{1, 2, 3}
>>> print (type(a))                    ## Prints "<class 'set'>"
>>> a[1]                               ## As you can see in here, you cannot index anyone in the set. 
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'set' object does not support indexing
>>> a[0]
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: 'set' object does not support indexing
>>> l1 = list(a)                       ## another way to use list
>>> l1
[1, 2, 3]
>>> print (type(l1))                   ## Prints "<class 'list'>"
>>> l1[0]
1
>>> l1[2]
3
>>> t1 = tuple(a)                      ## the other way to use tuple
>>> t1
(1, 2, 3)
>>> print (type(t1))
<class 'tuple'>
>>> t1[1]
2
>>> t1[2]
3

>>> s1 = set ([1,2,3,4,5,6])
>>> s1
{1, 2, 3, 4, 5, 6}
>>> s2 = set ([4,5,6,7,8,9])
>>> s2
{4, 5, 6, 7, 8, 9}
>>> s1 & s2                     ## intersection of sets. 
{4, 5, 6}
>>> s1.intersection(s2)
{4, 5, 6}
>>> s1 | s2                     ## sum of sets. 
{1, 2, 3, 4, 5, 6, 7, 8, 9}
>>> s1.union(s2)
{1, 2, 3, 4, 5, 6, 7, 8, 9}
>>> s1 - s2                     ## Difference of sets. 
{1, 2, 3}
>>> s2 - s1
{8, 9, 7}
>>> s1.difference(s2)
{1, 2, 3}
>>> s2.difference(s1)
{8, 9, 7}

>>> s1 = set([1,2,3])
>>> s1
{1, 2, 3}
>>> print (type(s1))              ## Prints "<class 'set'>"
>>> s1.add(4)                               ## just to add one factor
>>> s1
{1, 2, 3, 4}
>>> s1.add([5,6,7])
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
TypeError: unhashable type: 'list'
>>> s1.update([4,5,6])                      ## just to add a bunch of factors
>>> s1
{1, 2, 3, 4, 5, 6}
>>> s1.remove(2)
>>> s1
{1, 3, 4, 5, 6}

>>> pocket = ['paper', 'cell phone', 'money']
>>> card  = 1
>>> if '100 dollar' in pocket :                       ## If statement of python cosists of if ~ elif ~ else. 
...     print ("I'm rich")                            ## you need to be careful, don't forget ":(colone)", 
... elif card :
...     print ("I have a money a little bit")
... else :
...     print ("I have others, paper and cell phone")
...
I have a money a little bit                           ## what is the pass ? this just literally means the meaning of pass 
>>> if '100 dollar' in pocket :                       ## this is useful in If or class 
...     print ("I'm rich")
... elif card:
...     pass
... else :
...     print ("I have others, paper and cell phone")
...
>>> if '100 dollar' in pocket : pass                  ## in here, this show you how to represent statement in a line 
... else : print ("I have a others, paper and cell phone")    ## when if has one statement 
...
I have a others, paper and cell phone

>>> coffee = 0                                        ##  you can see the basic operation of while statement of python
>>> while coffee < 10 :
...     coffee += 1
...     print ("today you have drunk %d cups of coffee" % coffee)
...     if coffee == 10 :
...             print ("we do not have coffee at all")
...
today you have drunk 1 cups of coffee
today you have drunk 2 cups of coffee
today you have drunk 3 cups of coffee
today you have drunk 4 cups of coffee
today you have drunk 5 cups of coffee
today you have drunk 6 cups of coffee
today you have drunk 7 cups of coffee
today you have drunk 8 cups of coffee
today you have drunk 9 cups of coffee
today you have drunk 10 cups of coffee
we do not have coffee at all

>>> coffee = 0                                        ## one is differenct from the above, just In here, I used "break" keyword
>>> while coffee < 10 :
...     coffee = coffee + 1
...     print ("Today, you have drunk % cups of coffee" % coffee)
...     if coffee == 2 :
...             print ("Sorry, we made a mistake of counting coffee!")
...             print ("So you cannot sell it")
...             break
...     if coffee == 10 :
...             print ("our coffee sold out")
...
Today, you have drunk 1 cups of coffee
Today, you have drunk 2 cups of coffee
Sorry, we made a mistake of counting coffee!
So you cannot sell it

>>> coffee = 0                                        ## this's also different, just one, in here I used "continue" keyword
>>> while coffee < 10 :
...     coffee = coffee + 1
...     print ("Today, you have drunk %d cups of coffee" % coffee)
...     if coffee == 2 :
...             continue
...             print ("Sorry, you made a mistake of counting coffee")
...             print ("So, you cannot sell it")
...     if coffee == 10 :
...             print ("our coffee sold out")
...
Today, you have drunk 1 cups of coffee
Today, you have drunk 2 cups of coffee
Today, you have drunk 3 cups of coffee
Today, you have drunk 4 cups of coffee
Today, you have drunk 5 cups of coffee
Today, you have drunk 6 cups of coffee
Today, you have drunk 7 cups of coffee
Today, you have drunk 8 cups of coffee
Today, you have drunk 9 cups of coffee
Today, you have drunk 10 cups of coffee
our coffee sold out

>>> score = [90, 25, 67, 45, 80]                         ## The basic for statement
>>> number = 0
>>> for test in score :
...     number += 1
...     if test > 60 :
...             print ("%d-th student pass, becuase the score is %d" % (number, test))
...     else :
...             print ("%d-th student fail, becuase the score is %d" % (number, test))
...
2-th student pass, becuase the score is 90
3-th student fail, becuase the score is 25
4-th student pass, becuase the score is 67
5-th student fail, becuase the score is 45
6-th student pass, becuase the score is 80

>>> score = [90, 25, 67, 45, 80]                         ## for statement with continue keyword
>>> number = 0
>>> for test in score :
...     number += 1
...     if test < 60 : continue
...     print ("%d-th student pass, because the score is %d" % (number , test))
...
1-th student pass, because the score is 90
3-th student pass, because the score is 67
5-th student pass, because the score is 80

>>> score = [90, 25, 67, 45, 80]                         ## for statement with pass keyword
>>> number = 0
>>> for test in score :
...     number += 1
...     if test < 60 : pass                              ## without else keyword
...     print ("%d-th student pass, because the score is %d" % (number, test))
...
1-th student pass, because the score is 90
2-th student pass, because the score is 25
3-th student pass, because the score is 67
4-th student pass, because the score is 45
5-th student pass, because the score is 80

>>> score = [90, 25, 67, 45, 80]
>>> number  = 0
>>> for test in score :
...     number += 1
...     if test < 60 : pass                              ## including else keyword
...     else : print("%d-th student pass, because the score is %d" % (number, test))
...
1-th student pass, because the score is 90
3-th student pass, because the score is 67
5-th student pass, because the score is 80

>>> score = [90, 25, 67, 45, 80]                         ## for statement with break keyword
>>> number = 0
>>> for test in score :
...     number += 1
...     if test < 60 : break
...     print ("%d-th student pass, because the score is %d" % (number, test))
...
1-th student pass, because the score is 90


>>> sum = 0
>>> for i in range(0, 10) :                             ## what kind of role is range function
...     sum += i
...     print ("sum : %d" % sum)
...
sum : 0
sum : 1
sum : 3
sum : 6
sum : 10
sum : 15
sum : 21
sum : 28
sum : 36
sum : 45

>>> sum = 0
>>> range(10)
range(0, 10)
>>> for i in range(10) :
...     sum += i
...     print ("sum: %d" % sum)
...
sum: 0
sum: 1
sum: 3
sum: 6
sum: 10
sum: 15
sum: 21
sum: 28
sum: 36
sum: 45

>>> for i in range(2, 10) :                             ## with two for statements
...     for j in range (1, 10) :
...             print ("%d*%d : %d " % ( i, j , i*j), end = " " )
...     print ("")
...
2*1 : 2  2*2 : 4  2*3 : 6  2*4 : 8  2*5 : 10  2*6 : 12  2*7 : 14  2*8 : 16  2*9 : 18
3*1 : 3  3*2 : 6  3*3 : 9  3*4 : 12  3*5 : 15  3*6 : 18  3*7 : 21  3*8 : 24  3*9 : 27
4*1 : 4  4*2 : 8  4*3 : 12  4*4 : 16  4*5 : 20  4*6 : 24  4*7 : 28  4*8 : 32  4*9 : 36
5*1 : 5  5*2 : 10  5*3 : 15  5*4 : 20  5*5 : 25  5*6 : 30  5*7 : 35  5*8 : 40  5*9 : 45
6*1 : 6  6*2 : 12  6*3 : 18  6*4 : 24  6*5 : 30  6*6 : 36  6*7 : 42  6*8 : 48  6*9 : 54
7*1 : 7  7*2 : 14  7*3 : 21  7*4 : 28  7*5 : 35  7*6 : 42  7*7 : 49  7*8 : 56  7*9 : 63
8*1 : 8  8*2 : 16  8*3 : 24  8*4 : 32  8*5 : 40  8*6 : 48  8*7 : 56  8*8 : 64  8*9 : 72
9*1 : 9  9*2 : 18  9*3 : 27  9*4 : 36  9*5 : 45  9*6 : 54  9*7 : 63  9*8 : 72  9*9 : 81

>>> a = [1,2,3,4]                           ## everyone of a List time 3 using for statement 
>>> result = []                             ## to insert the itme into result variable of list
>>> for num in a :
...     result.append(num*3)
...
>>> result
[3, 6, 9, 12]
>>> result = [num * 3 for num in a]         ## BUT, if you use List comprehension, 
>>> result                                  ## your task is so easy to make new list with some other List
[3, 6, 9, 12]
>>> result = [num * 3 for num in a if num % 2 == 0]     ## with List Comprehension and if statement in List comprehension
>>> result
[6, 12]

>>> result = [x*y for x in range(2,10)
...               for y in range(1,10)]
>>> result                                        ## in order to show you easily how to use two variable in List comprehension
[2, 4, 6, 8, 10, 12, 14, 16, 18, 
3, 6, 9, 12, 15, 18, 21, 24, 27, 
4, 8, 12, 16, 20, 24, 28, 32, 36, 
5, 10, 15, 20, 25, 30, 35, 40, 45, 
6, 12, 18, 24, 30, 36, 42, 48, 54, 
7, 14, 21, 28, 35, 42, 49, 56, 63, 
8, 16, 24, 32, 40, 48, 56, 64, 72, 
9, 18, 27, 36, 45, 54, 63, 72, 81]

>>> def sum(a,b) :                 ## with arguments and return value
...     return a+b
...
>>> sum(1,3)
4

>>> def say():                     ## with no arguments and return value
...     return  "Hi"
...
>>> say()
'Hi'

>>> def sum(a, b):                 ## with arguments and no return value
...     print ("%d + %d = %d" % (a, b, a+b))
...
>>> sum( 3, 7)
3 + 7 = 10

>>> def say() :                    ## with no arguments and no return value
...     print ("hello!")
...
>>> say()
hello!

>>> def sum(*args) :              ## In order to get arguments randomly. 
...     sum = 0                   ## * is used to do that   
...     for i in args :
...             sum = sum + i
...     return sum
...
>>> sum(1,2,3,4,5)
15
>>> sum(1,2,3,4,5,6,7)
28
>>> sum(1,2,3,4,5,6,7,8,9)
45
>>> a, b = sum_and_mul(3, 7)
>>> a
10
>>> b
21
>>> type(a)                 ## Return "<class 'int'>"
>>> type(b)                 ## Return "<class 'int'>"

>>> def say_nickname(nick) :       ## you don't have to use return keyword with value that you'r goind to return. 
...     if nick == "stupid" :
...             return
...     print ("my nickname is %s " % nick)
...
>>> say_nickname("stupid")
>>> say_nickname("stupid!")
my nickname is stupid!

>>> def let_me_introduce_myself(name, old, gender = True) :           ## with arguments initialized. 
...     print ("my name is %s" % name)
...     print ("my age is %s" % old)
...     if gender == True :
...             print ("my gender is male")
...     else :
...             print ("my gender is female")
...
>>> let_me_introduce_myself("hyunyoung2", "20")
my name is hyunyoung2
my age is 20
my gender is male
>>> let_me_introduce_myself("hyunyoung2", "20", False)
my name is hyunyoung2
my age is 20
my gender is female

>>> def let_me_introduce_myself(name, gender = True, old) :
...     print ("my name is %s" % name)
...     print ("my age is %s" % old)
...     if gender == True :
...             print ("my gender is male")
...     else :
...             print ("my gender is female")
...
  File "<stdin>", line 1
SyntaxError: non-default argument follows default argument


>>> def sum(a, b):            ## only in the case of python as you can see, 
...     return a+b, a-b       ## python returns a couple of variables, the type of retun values is tuple. 
...
>>> return_value = sum(5, 5)
>>> return_value
(10, 0)
>>> type(return_value)
<class 'tuple'>

>>> class HouseLee :                      ## parent class
...     lastname = "Lee"
...     def __init__(self, name):         ## constructor
...             self.fullname = self.lastname + name
...     def travel(self, where) :
...             print ("%s goes to %s" % (self.fullname, where))
...     def love(self, other) :
...             print ("%s falls in love with %s" % (self.fullname, other.fullname))
...     def fight(self, other) :
...             print ("%s fought %s" % (self.fullname, other.fullname))
...     def __add__(self, other) :        ## class overloading
...             print ("%s was married with %s" % (self.fullname, other.fullname))
...     def __sub__(self, other) :        ## class overloading
...             print ("%s was divorced from %s" % (self.fullname, other.fullname))
...
>>> class HouseNa (HouseLee) :            ## Inheritance of class
...     lastname = "Na"
...     def travel(self, where, day) :    ## overriding function of class 
...             print ("%s, to %s for %d days" % (self.fullname, where, day))
...

>>> romio = HouseLee(" HY")               ## create class 1
>>> juliet = HouseNa(" YJ")               ## create class 2
>>> romio.travel("Busan")                 ## function call of class 1
Lee HY goes to Busan
>>> juliet.travel("Busan", 3)             ## function call of class 2 overriding
Na YJ, to Busan for 3 days
>>> juliet.travel("Busan")
Traceback (most recent call last):        ## error in the number of arguments of function of class 2
  File "<stdin>", line 1, in <module>
TypeError: travel() missing 1 required positional argument: 'day'
>>> romio.love(juliet)
Lee HY falls in love with Na YJ
>>> romio + juliet                        ## overloading of + operator
Lee HY was married with Na YJ
>>> romio.fight(juliet)
Lee HY fought Na YJ     
>>> romio - juliet                        ## overloading of - operator
Lee HY was divorced from Na YJ

# mod1.py
def sum(a, b) :
    return a+b

>>> import mod1
>>> mod1.sum(1,2)
3
>>> from mod1 import sum
>>> sum(1,2)
3
>>> import mod1 as test
>>> test.sum(1,2)
3
>>> from mod1 import sum as t
>>> t(1,2)
3

import game.sound.echo
game.sound.echo.echo_test()  ## function call 


from game.sound import echo
echo.echo_test()             ## function call from moudle 

from game.sound.echo import echo_test
echo_test()                  ## function call directly as function name

try : 
  f = open ("file.txt", "r")
except FileNotFoundError as e :
  print (str(e))
else :
  data = f.read()
  f.close()
finally :
  print ("this is executed if error happens or not")

>>> sum = lambda a, b : a+b
>>> sum(3,4)
7

>>> myList = [lambda a, b : a+b, lambda a,b :a*b]
>>> myList
[<function <lambda> at 0x032F6660>, <function <lambda> at 0x032F6618>]
>>> myList[0]
<function <lambda> at 0x032F6660>
>>> myList[0](3,4)
7
>>> myList[1](3,4)
12

>>> def two_times(numberList):                   ## before using map function 
...     result = []
...     for number in numberList :
...             result.append(number*2)
...     return result
...
>>> return_value = two_times([1,2,3,4,5])
>>> type(return_value)            ## Return "<class 'list'>"
>>> return_value
[2, 4, 6, 8, 10]

>>> def twoTimes(x): return x*2                  ## function definition to start off with map function 
...
>>> map(twoTimes, [1,2,3,4,5])                   ##  What is the map ? just object 
<map object at 0x032F4BD0>
>>> list(map(twoTimes, [1,2,3,4,5]))             ## to make  return value of map list
[2, 4, 6, 8, 10]
>>> list(map(lambda a: a*2, [1,2,3,4]))          ## if you use lambda instead of map function. 
[2, 4, 6, 8]