reference:



In [5]:

    
x = 1
if x == 1:
    # indented four spaces
    print "x is 1."









    



x is 1.

Variable type

命名規則？

A valid identifier is a non-empty sequence of characters of any length with:

the start character can be the underscore "_" or a capital or lower case letter
the letters following the start character can be anything which is permitted as a start character plus the digits.
Just a warning for Windows-spoilt users: Identifiers are case-sensitive
Python keywords are not allowed as identifier names



In [ ]:



In [2]:

    
myfloat = 7.0
myfloat = float(7)



In [3]:

    
mystring = 'hello'
mystring = "hello"



In [4]:

    
one = 1
two = 2
three = one + two

hello = "hello"
world = "world"
helloworld = hello + " " + world



In [8]:

    
a, b = 3, 4

LIST



In [3]:

    
mylist = [1,2,3,4,5,"test","test2"]



In [5]:

    
mylist









    Out[5]:





[1, 2, 3, 4, 5, 'test', 'test2']



In [7]:

    
mylist[1]









    Out[7]:





2



In [10]:

    
mylist = []
for i in range(100):
    mylist.append(i)



In [48]:

    
mylist2 = [(i+2)*2 for i in range(10)]



In [49]:

    
mylist2









    Out[49]:





[4, 6, 8, 10, 12, 14, 16, 18, 20, 22]



In [9]:

    
mylist = []
mylist.append(1)
mylist.append(2)
mylist.append(3)
print(mylist[0]) # prints 1
print(mylist[1]) # prints 2
print(mylist[2]) # prints 3

# prints out 1,2,3
for x in mylist:
    print x



In [35]:

    
mylist = [1,2,3,4,5,6]
print(mylist[10])









    



---------------------------------------------------------------------------
IndexError                                Traceback (most recent call last)
<ipython-input-35-af8112443d7b> in <module>()
      1 mylist = [1,2,3,4,5,6]
----> 2 print(mylist[10])

IndexError: list index out of range



In [50]:

    
mylist2









    Out[50]:





[4, 6, 8, 10, 12, 14, 16, 18, 20, 22]



In [67]:

    
mylist2[::-2]









    Out[67]:





[22, 18, 14, 10, 6]



In [143]:

    
x = [1,2,3,4]



In [144]:

    
x[1:2]









    Out[144]:





[2]

Dictionary



In [78]:

    
phonebook = {}
phonebook["John"] = {'age':42423,'tel':[938477566,412414124]}
phonebook["Jack"] = 938377264
phonebook["Jill"] = 947662781



In [80]:

    
phonebook  #key:value









    Out[80]:





{'Jack': 938377264,
 'Jill': 947662781,
 'John': {'age': 42423, 'tel': [938477566, 412414124]}}



In [82]:

    
phonebook['John']['age']









    Out[82]:





42423



In [3]:

    
phonebook = {
    "John" : 938477566,
    "Jack" : 938377264,
    "Jill" : 947662781
}



In [86]:

    
del phonebook["John"]



In [101]:

    
phonebook['Paul']=4924791827



In [102]:

    
phonebook









    Out[102]:





{'Jack': 938377264, 'Jill': 947662781, 'Paul': 4924791827}

Operation



In [12]:

    
number = 1 + 2 * 3 / 4.0



In [13]:

    
remainder = 11 % 3



In [14]:

    
squared = 7 ** 2
cubed = 2 ** 3



In [105]:

    
lotsofhellos = "hello " * 10



In [106]:

    
lotsofhellos









    Out[106]:





'hello hello hello hello hello hello hello hello hello hello '



In [108]:

    
even_numbers = [2,4,6,8]
odd_numbers = [1,3,5,7]
all_numbers = odd_numbers + even_numbers



In [109]:

    
all_numbers









    Out[109]:





[1, 3, 5, 7, 2, 4, 6, 8]



In [110]:

    
print [1,2,3] * 3









    



[1, 2, 3, 1, 2, 3, 1, 2, 3]

Operator	Description	Example
+, -	Addition, Subtraction	10 -3
*, /, %	Multiplication, Division, Modulo	27 % 7 Result: 6
//	Truncation Division (also known as floordivision) The result of the division is truncated to an integer. Works for integers and floating-point numbers as well	27 // 7 Result: 6
+x, -x	Unary minus and Unary plus (Algebraic signs)	-3
~x	Bitwise negation	~3 - 4 Result: -8
**	Exponentiation	10 ** 3 Result: 1000
or, and, not	Boolean Or, Boolean And, Boolean Not	(a or b) and c
in	"Element of"	1 in [3, 2, 1]
<, <=, >, >=, !=, ==	The usual comparison operators	2 <= 3
, &, ^	Bitwise Or, Bitwise And, Bitwise XOR	6 ^ 3
<<, >>	Shift Operators	6 << 3



In [122]:

    
11.0/2









    Out[122]:





5.5



In [126]:

    
x = 11
y = 2
print(float(x)/y)

5.5



In [132]:



In [133]:









    Out[133]:





2384370293875403298570923875093L

String Formating



In [134]:

    
name = "John"
print "Hello, %s!" % name









    



Hello, John!



In [135]:

    
print "Hello " + name + "!"









    



Hello John!



In [136]:

    
# This prints out "John is 23 years old."
name = "John"
age = 23
print "%s is %d years old." % (name, age)









    



John is 23 years old.



In [137]:

    
# This prints out: A list: [1, 2, 3]
mylist = [1,2,3]
print "A list: %s" % mylist









    



A list: [1, 2, 3]

%s - String (or any object with a string representation, like numbers) %d - Integers %f - Floating point numbers %.f - Floating point numbers with a fixed amount of digits to the right of the dot. %x/%X - Integers in hex representation (lowercase/uppercase)



In [139]:

    
name









    Out[139]:





'John'



In [140]:

    
print(name[0])
print(name[1])

J
o



In [142]:

    
name[1:3]









    Out[142]:





'oh'



In [17]:

    
name[1:3]









    Out[17]:





'oh'



In [145]:

    
name[::-1]









    Out[145]:





'nhoJ'



In [29]:

    
name[0:4:2]









    Out[29]:





'Jh'



In [30]:

    
name[0::2]









    Out[30]:





'Jh'



In [31]:

    
name[::-1]









    Out[31]:





'nhoJ'



In [158]:

    
x = 'I am a student'.split(' ')



In [160]:









    Out[160]:





list



In [ ]: