First, integer
Python integers of any size can be treated, including negative integer, hexadecimal integer with a prefix 0x hexadecimal and 0-9, af represent, for example: 0xff00
Second, the float
That is decimal floating-point number can be 1.23,3.14, -9.9 ,, may also be expressed mathematically written in scientific notation, with the 10 e alternative, 1.23x10 ^ 9 12.3e8,0.000012 written or written 1.23e9 1.2e-5
Third, the string
String is '' or '' enclose any text, such as 'abc', "xyz"
Fourth, the Boolean value
Only Boolean value True, False, can be directly expressed, can be calculated by Boolean operators
Boolean values can be used and, or and not operator
and operation: only if all are True, and operation is True
or operation: one of them is True, or operations on to True
not operational: True becomes False, False becomes True
Fifth, null
Python in a special value, None
Six variables
In Python, variable names must be a combination of English case, numbers and underscores, and can not begin with a number
Python is a dynamic language, you can assign the same variable repeatedly, it can be different types of variables
Seven list: list
list is an ordered set, which you can add and remove elements at any time, list of elements contained in data need not be of the same type
student=['Michale','Bob','Tracy']
L=['A',123,True]
empty_list=[]
Access list elements
Access List by index, the index starting from 0, for example, print student [0]
Reverse access, index starting at -1, e.g. print student [-1]
Taken characters [index1: index2], does not include an element index index2, e.g. list = [1,2,3,4,5] print student [1: 3] Results [2,3]
list add and delete new elements:
student.append ( 'Sam'), append () to add a new element to the tail of --student list = [ 'Michale', 'Bob', 'Tracy', 'Sam']
student.insert (0, 'Paul'), insert (index, temp) to add new elements to the corresponding position, the rear element is automatically moved back --student = [ 'Paul', 'Michale', 'Bob', 'Tracy' , 'Sam']
student.pop (), pop () to delete the last element --student = [ 'Paul', 'Michale', 'Bob', 'Tracy']
del student [1], del delete elements
list method:
len (list): a list of the number of elements
max (list): a list of the largest element
min (list): a list of the minimum element
Eight-tuple: tuple
Tuples use parentheses, and a list of similar, but can not modify the elements of the tuple
t=('physics',2000,'a')
Empty tuple t = ()
Only one tuple element t = (1,)
tuple access elements:
Accessed by index, the index starting from 0, for example, t [0]
Theme elements using brackets [index1: index2], does not include an element index index2, e.g. t2 = (1,2,3,4,5,6) print t2 [1: 5] results (2,3,4, 5)
tuple method:
Comparison of the two elements of tuples: cmp (tuple1, tuple2)
Tuple number of elements: len (tuple)
max (tuple): the maximum element tuple
min (min): the minimum element tuple
tuple (sep): to convert into a list of tuples
IX dictionary: Dictionary
Dictionary is a variable container model, may store any type of objects, each key-value dictionary separated by a colon, separated by a comma between each key value contained in the entire dictionary braces
dict={'name':'Sam','age':8,'class':'First'}
Access elements:
With access key, e.g. dict [ 'name'], dict [ 'age']
Updated Dictionary:
Add new key pair, e.g. dict [ 'score'] = 100
Update key-value pair, such dict [ 'age'] = 9
Delete the key pair, e.g. del dict [ 'score']
Empty dictionary, for example dict.clear ()
Delete dictionary, del dict
Dictionary features:
1, with a duplicate key is assigned, it will only remember the latest assignment
2, the key immutable
Dictionary built-in methods:
cmp (dict1, dict2): comparison of two dictionary size
len (dict): counting the number of dictionaries
Dictionary of built-in functions:
Returns true key to determine whether or not in the dictionary, there is: dict.has_key (key)
dict.keys (): returns a list of all the keys
dict.values (): to return all the values
X. collection: set
set is a series of non-repeating element, unordered collection. Create a set way is to call set () and passing in a list, list of elements as a set of elements
s=set(['A','B','C'])
When the set can not contain duplicate elements, comprising a list of incoming duplicate elements, the elements will automatically remove duplicate
Access elements:
unordered set of elements, can not all need to first determine whether there is an element, it can be used in operator judgment
Traversal set:
For loop
Update set:
Add set with additive elements () method, e.g. s.add ( 'C')
Delete elements with remove set () method, e.g. s.remove ( 'A'), before removing the elements necessary to determine whether there is no error present will delete