Basic operations of the python dictionary and basic operations of python

Basic operations of the python dictionary and basic operations of python

Basic dictionary Methods

What is a dictionary:

A dictionary is a key-value data type. It sounds like a dictionary we use in school. We use strokes and letters to find the details of the drinking page.

Syntax:

id_dict = {    'stu1101': "TengLan Wu",    'stu1102': "LongZe Luola",    'stu1103': "XiaoZe Maliya",}

 

Dictionary features:

Dict is unordered

Key must be unique, value can be repeated, key = key, value = value

 

Added:

id_dict["stu1104"] = "smelond"print(id_dict){'stu1101': 'TengLan Wu', 'stu1102': 'LongZe Luola', 'stu1103': 'XiaoZe Maliya', 'stu1104': 'smelond'}

 

Modify:

id_dict["stu1101"] = "amanda"print(id_dict){'stu1101': 'amanda', 'stu1102': 'LongZe Luola', 'stu1103': 'XiaoZe Maliya'}

 

Delete an item:

Print (id_dict)
{'Stu1101': 'tenglan wu', 'stu1102': 'longze Luola ', 'stu1103': 'xiaoze Maliya '}

Id_dict.pop ("stu1101") # standard Deletion
Print (id_dict)
{'Stu1102': 'longze Luola ', 'stu1103': 'xiaoze Maliya '}

 

Del deletion:

Print (id_dict) {'stu1101': 'tenglan wu', 'stu1102': 'longze Luola ', 'stu1103 ': 'aoze Maliya '} del id_dict ["stu1101"] # del Delete print (id_dict) {'stu1102': 'longze Luola', 'stu1103': 'xiaoze Maliya '}

 

Random deletion:

Print (id_dict) {'stu1101': 'tenglan wu', 'stu1102': 'longze Luola ', 'stu1103': 'xiaoze Maliya'} id_dict.popitem () # randomly Delete print (id_dict) {'stu1101': 'tenglan wu', 'stu1102': 'longze Luola '}

 

Delete the dictionary directly:

Print (id_dict) id_dict.clear () # delete all content in the dictionary print (id_dict) {'stu1101': 'tenglan wu', 'stu1102': 'longze Luola ', 'stu1103': 'xiaoze Maliya '}{}

 

Search:

Print ("stu1101" in id_dict) # in check whether this object is True # If yes, fFalse

 

Obtain:

Print (id_dict.get ("stu1101") # Use get to obtain the key value if it exists. If it does not exist, None, TengLan Wu is returned.
Print (id_dict ["stu1101"]) # This method will not be as intelligent as it is above. If the key does not exist, TengLan Wuprint will be reported directly (id_dict ["stu11231"]). print (id_dict ["studen31"]) KeyError: 'studen31'

 

Multi-dictionary nesting:

#! /Usr/bin/env python # _ * _ coding: UTF-8 _ * _ # File_type: Multi-dictionary nesting # Filename: dict_nest.py # Author: smelondid_dict = {"ChengDu ": {"acreage": 14312, "population": "1591.8 w", "postalcode": 610000}, "ShenZhen": {"acreage": 1196, "population ": "1190.08 w", "postalcode": 518000}, "BeiJing": {"acreage": "1.641 w", "population": "2172.9 w", "postalcode ": 100000} print (id_dict ["ChengDu"]) # print all output values
Print (id_dict ["ChengDu"] ["acreage"]) # print the area of the output ChengDu
Id_dict ["ChengDu"] ["acreage"] = "Area: 14312 square kilometers" # change the area of ChengDu to "Area: 14312 square kilometers"
Print (id_dict ["ChengDu"] ["acreage"]) # print

{'Acreage': 14312, 'population': '2017. 8w', 'postalcode': 1591}
14312
Area: 14312 square kilometers

 

Convert a dictionary to a tuples:

print(id_dict.items())dict_items([('stu1101', 'TengLan Wu'), ('stu1102', 'LongZe Luola'), ('stu1103', 'XiaoZe Maliya')])

 

Convert a dictionary to a list:

list_test = list(id_dict)print(list_test)['stu1101', 'stu1102', 'stu1103']

 

Dictionary cycle:

For key in id_dict: print (key, id_dict [key]) # as a key is added, stu is also cyclically output: stu1101 TengLan Wustu1102 LongZe Luolastu1103 XiaoZe Maliyafor key in id_dict: print (id_dict [key]) Output: TengLan WuLongZe LuolaXiaoZe Maliya

 

Multi-dictionary nested loop:

#! /Usr/bin/env python # _ * _ coding: UTF-8 _ * _ # File_type: Multi-dictionary nesting # Filename: dict_nest.py # Author: smelondid_dict = {"ChengDu ": {"acreage": 14312, "population": "1591.8 w", "postalcode": 610000}, "ShenZhen": {"acreage": 1196, "population ": "1190.08 w", "postalcode": 518000}, "BeiJing": {"acreage": "1.641 w", "population": "2172.9 w", "postalcode ": 100000} for key in id_dict: # Still loop test = id_dict [key] # assign each key to test for key in test: # loop test # print (key, ":", test [key], "\ n", end = "") print ("% s: % s "% (key, test [key]) # print the second-level key and the valueacreage: 14312 population: 1591.8 wpostalcode: 610000 acreage: 1196 population: 1190.08 wpostalcode: 518000 acreage: 1.641 wpopulation: 2172.9 wpostalcode: 100000