Python Learning Notes (iv) Python object types and their operations

Related terms for Python objects:

All the data stored in a Python program is built around the concept of the object.

• All data stored in the program is an object

• Each object has an identity, a type, and a value

  • For example, school= "MaGe Linux" creates a string object with "MaGe Linux" whose identity is a pointer to its location in memory (its address in memory), and school is the name that refers to that particular location.

in [+]: name= "Herry" in []: ID (name) out[15]: 40364672In [+]: type (name) out[16]: str

The type of an object also becomes the category of the object that describes the internal representation of the object and the methods and actions it supports to create a particular type of object, and sometimes the instance of the object that becomes the type is created, and its identity and type cannot be changed

• If the object is modifiable, it is called a mutable object

• If the value of an object cannot be changed, it is called an immutable object

  
  

  
  

If an object contains references to other objects, it is called a container most objects have a large number of unique data properties and methods

• Properties: Values associated with an object

• Method: A function that will perform certain operations on an object when called

• Use (.) Operators can access properties and methods

  
  

Classes: Data and methods

Data: Variables

Method: function

Class (instantiated as an object)

Python built-in function ID () returns the identity of an object, both in-memory location

• The IS operator is used to compare the identities of two objects

• Type () to return the types of an object

#两个对象比较: #1. Value comparison: Whether the data in the object is the same #2. Identity comparison: Two variable names refer to the same object #3. Type comparison: Two objects are of the same type in []: name1= "Tom" in [Max]: name2= "Tom" in [+]: name3= "Jack" in [[]: name1==name2out[24]: Truein []: Name1 is name2out[20]: Truein []: Name1 is name3out[21]: Fa Lsein [+]: type (NAME1) is type (name2) out[22]: True

Python Core Data type:

Numbers: Int,log,float,complex,bool

Character: Str,unicode

Listing: List

Tuples: Tuple

Files: File

Other types: Collection (set), Fronzenset, class type, none

Other file class Tools: Pipes (Pipeline), FIFO (first in, out pipe), sockets (socket)

The type of the object is itself an object, called the class of the object

• The definition of the object is unique and is the same for all instances of a type

• All types of objects have a specified name that can perform type checking, such as List,dict

Type conversions:

str (),repr ( ), or format (): Converts non-character data to characters:

In []: name1==name2out[24]: Truein [+]: num1=5.61in [+]: type (NUM1) out[26]: Floatin [+]: str (NUM1) out[27]: ' 5.61 ' in [ : num1=5.61in []: Str1=repr (NUM1) in [+]: type (STR1) out[30]: str

Int (): Convert to Integer

Float (): Convert to floating point

List (s): Convert string S to list

Tuples (s): convert string s to Narimoto group

Set (s): Convert string S to collection

Dict (d): Create dictionary, where D is (key,value) tuple

In [31]: str2= "In [33]: type" (str2) Out[33]: strin [34]: num3=int (STR2) in  [35]: type (num3) out[35]: intin [36]: num4=float (str2) in [37]: type (NUM4) out[37]: floatin [38]: str3= "Whats you name" #将字符穿转换列表 (list) type in [39]: l1= List (STR3) in [40]: print l1[' W ',  ' h ',  ' a ',  ' t ',  ' s ',  '   ',  ' Y ',  ' o ',  ' u ',  '   ',  ' n ',  ' a ',  ' m ',  ' e ']in [41]: str4= ' whats  the fuck "#将字符串转换为元组In  [42]: t1=tuple (STR4) in [44]: print t1 (' W ',  ' h ',   ' a ',  ' t ',  ' s ',  '   ',  ' t ',  ' h ',  ' e ',  '   ',  ' f ',  ' u ',   ' C ',  ' K ') #将字符串转换成集合In  [45]: print str4whats the fuckin [46]: s1= Set (STR4) In [47]: print s1set ([' A ',  '   ',  ' C ',  ' e ',  ' F ',  ' H ',   ' K ',  ' s ',   ' U ',  ' t ',  ' W ') #将数组转换成字典In  [51]: l3=[(' A ', 1), (' B ', '), (' C ', ', ')]in [52]: print  l3[(' A ',  1),  (' B ',  22),  (' C ',  56)]in [53]: d1=dict (L3) in [54]:  print d1{' A ': 1,  ' C ': 56,  ' B ':  22}

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Python Learning Notes (iv) Python object types and their operations