Basic syntax:
dict = {'ob1':'computer', 'ob2':'mouse', 'ob3':'printer'}
Tips:
The dictionary contains lists: dict={'yangrong':['23','IT'],"xiaohei":['22','dota']}
The dictionary contains dictionaries: dict={'yangrong':{"age":"23","job":"IT"},"xiaohei":{"'age':'22','job': 'dota'"}}
Available commands:
root@yangrong:~# cd /python
root@yangrong:/python# python
Python 2.7.5+ (default, Sep 19 2013,13:48:49)
[GCC 4.8.1] on linux2
Type "help","copyright", "credits" or "license" for moreinformation.
>>> ; import tab
>>> d={}
>>> d.
d.class( d.ge( d.len ( d.setitem( d.has_key( d.setdefault(
d.cmp( d.lt( d.sizeof( d.items( d.items( d.update(
d .contains( d.getitem( d.ne( d.str( d.iteritems( d.values(
d.delattr( d.gt( d.new( ) d.subclasshook( d.iterkeys( d .viewitems(
d.delitem( d.hash d.reduce( d.clear( d.itervalues(
d.doc d.init( d.reduce_ex( d .copy (
d.format( d.le ( d.setattr( d.get( d.popitem( d.popitem() {}
>>> nameinfo['a1']='yangrong' #If there is a1 primary key in the dictionary, overwrite the original value, if not, add
> >> nameinfo
{'a1': 'yangrong'}
Traverse the dictionary primary key and key value
>>> for k, value innameinfo. items():
... print k,value
...
a1 yangrong
View all primary keys in the dictionary
>>> dict = {'ob1':'computer','ob2' :'mouse', 'ob3':'printer'}
>>>
>>>
>>> dict .keys()
['ob2', 'ob3', 'ob1']
Determine whether the primary key exists in the dictionary
>>> dict. keys()
['ob2', 'ob3', 'ob1']
>>> dict.has_key('ob2') #or'ob2' in dict
True
>>> dict.has_key('ob4')
False
Some people also use the loop method To judge
for key in dict.keys():
But this method is not concise enough after all,
View all key value contents of the dictionary
> ;>> dict = {'ob1':'computer','ob2':'mouse', 'ob3':'printer'}
>>> dict.values()
['mouse', 'printer', 'computer']
List all items
>>> dict.items()
[('ob2', 'mouse'), ('ob3', 'printer'),('ob1', 'computer')]
Clear the dictionary
>> > dict.clear()
>>> dict
{}
Copy dictionary
>>> dict
{'ob2': 'mouse', 'ob3': 'printer', 'ob1':'computer'}
>>> a=dict
>>> a
{'ob2': 'mouse', 'ob3': 'printer', 'ob1':'computer'}
>>> b=dict.copy()
>>> b
{'ob2': 'mouse', 'ob3': 'printer', 'ob1': 'computer'}
Compare dictionary
>>> cmp(a,b)
First compare the primary key length, then compare the key size, and then compare the key value size, (No. A large one returns 1, a small one returns -1, the same returns 0)
Update dictionary
>>>dict={'yangrong':{"age":"23" ,"job":"IT"},"xiaohei":{"'age':'22','job':'dota'"}}
>>> dict
{'xiaohei':set(["'age':'22','job':'dota'"]), 'yangrong': {'age': '23', 'job':'IT '}}
>>> dict['xiaohei']=111 #Modify the first-level dictionary
>>> dict
{'xiaohei ': 111, 'yangrong': {'age': '23','job': 'IT'}}
>>> dict['yangrong']['age']= 25 #Modify the secondary dictionary
>>> dict
{'xiaohei': 111, 'yangrong': {'age': 25,'job': 'IT' }}
>>> dict={'yangrong':['23','IT'],"xiaohei":['22','dota']}
>>>dict['xiaohei'][1]="dota2" #Modify an item in the list in the dictionary, 1 represents the second string in the list.
>>> dict
{'xiaohei': ['22', 'dota2'], 'yangrong':['23', 'IT']}
Delete dictionary elements
>>> dict
{'xiaohei': ['22', 'dota2'], 'yangrong':['23', 'IT']}
>>> del dict['xiaohei'] #Delete xiaohei key value
>>> dict
{' yangrong': ['23', 'IT']}
>>> dict
{'yangrong': ['23', 'IT']}
>>>
>>> del dict['yangrong'][1] #Delete every 2-character value of the yangrong primary key
>> > dict
{'yangrong': ['23']}
Delete the entire dictionary
>>> dict
{' yangrong': ['23']}
>>> dict.clear() #Same as del dict
>>> dict
{ }
Split the string into a list
>>> s="hello world bye"
>>> s.split() # Used to read regular text, modify it using a list, and then write it to the file.
['hello', 'world', 'bye']
Convert the list to a string
S.split(str, ' ') #WillstringConvertlist, split by spaces
Storage dictionary (pickle serialization)
#Need to import the pickle module import pickle
Save the dictionary content to the file
f=file('data.txt','wb') #Create a new file data.txt, 'wb', b is an open block file, for Device files are useful
pickle.dump(a,f) #Serialize a and store it in the file
f.close()
Read the content into the dictionary (deserialize ization)
a=open('data.txt','rb') #Open file
print pickle.load(a) #Deserialize all contents
The above is the detailed content of Summary of usage of python dictionary operations. For more information, please follow other related articles on the PHP Chinese website!

Python's flexibility is reflected in multi-paradigm support and dynamic type systems, while ease of use comes from a simple syntax and rich standard library. 1. Flexibility: Supports object-oriented, functional and procedural programming, and dynamic type systems improve development efficiency. 2. Ease of use: The grammar is close to natural language, the standard library covers a wide range of functions, and simplifies the development process.

Python is highly favored for its simplicity and power, suitable for all needs from beginners to advanced developers. Its versatility is reflected in: 1) Easy to learn and use, simple syntax; 2) Rich libraries and frameworks, such as NumPy, Pandas, etc.; 3) Cross-platform support, which can be run on a variety of operating systems; 4) Suitable for scripting and automation tasks to improve work efficiency.

Yes, learn Python in two hours a day. 1. Develop a reasonable study plan, 2. Select the right learning resources, 3. Consolidate the knowledge learned through practice. These steps can help you master Python in a short time.

Python is suitable for rapid development and data processing, while C is suitable for high performance and underlying control. 1) Python is easy to use, with concise syntax, and is suitable for data science and web development. 2) C has high performance and accurate control, and is often used in gaming and system programming.

The time required to learn Python varies from person to person, mainly influenced by previous programming experience, learning motivation, learning resources and methods, and learning rhythm. Set realistic learning goals and learn best through practical projects.

Python excels in automation, scripting, and task management. 1) Automation: File backup is realized through standard libraries such as os and shutil. 2) Script writing: Use the psutil library to monitor system resources. 3) Task management: Use the schedule library to schedule tasks. Python's ease of use and rich library support makes it the preferred tool in these areas.

To maximize the efficiency of learning Python in a limited time, you can use Python's datetime, time, and schedule modules. 1. The datetime module is used to record and plan learning time. 2. The time module helps to set study and rest time. 3. The schedule module automatically arranges weekly learning tasks.

Python excels in gaming and GUI development. 1) Game development uses Pygame, providing drawing, audio and other functions, which are suitable for creating 2D games. 2) GUI development can choose Tkinter or PyQt. Tkinter is simple and easy to use, PyQt has rich functions and is suitable for professional development.


Hot AI Tools

Undresser.AI Undress
AI-powered app for creating realistic nude photos

AI Clothes Remover
Online AI tool for removing clothes from photos.

Undress AI Tool
Undress images for free

Clothoff.io
AI clothes remover

AI Hentai Generator
Generate AI Hentai for free.

Hot Article

Hot Tools

SublimeText3 English version
Recommended: Win version, supports code prompts!

mPDF
mPDF is a PHP library that can generate PDF files from UTF-8 encoded HTML. The original author, Ian Back, wrote mPDF to output PDF files "on the fly" from his website and handle different languages. It is slower than original scripts like HTML2FPDF and produces larger files when using Unicode fonts, but supports CSS styles etc. and has a lot of enhancements. Supports almost all languages, including RTL (Arabic and Hebrew) and CJK (Chinese, Japanese and Korean). Supports nested block-level elements (such as P, DIV),

MinGW - Minimalist GNU for Windows
This project is in the process of being migrated to osdn.net/projects/mingw, you can continue to follow us there. MinGW: A native Windows port of the GNU Compiler Collection (GCC), freely distributable import libraries and header files for building native Windows applications; includes extensions to the MSVC runtime to support C99 functionality. All MinGW software can run on 64-bit Windows platforms.

SublimeText3 Chinese version
Chinese version, very easy to use

SublimeText3 Mac version
God-level code editing software (SublimeText3)