The third of the Python Learning diary--Dictionary

First, the dictionary

A dictionary in Python is not a sequence, but rather a mapping; it is stored by key instead of by location. The dictionary is mutable.

1. Dictionary Mapping Operations

Using the {} definition dictionary to store data in key:value form, key is unique in the dictionary >>> one_dict = {' name ': ' Jym ', ' age ': ' addr ': ' Xinjiang '} #通过key查找数据 >>> one_dict[' name '] ' jym# modify >>> one_dict[' name '] = "Jym" >>> print (one_dict) {' name ': ' Jym ', ' Age ': "addr ': ' Xinjiang '}>>> one_dict[' age '] + = 1>>> Print (one_dict) {' name ': ' Jym ', ' age ': ', ' ad Dr ': ' Xinjiang '} #添加, directly assigning a key that is not in the dictionary, creates the key value >>> one_dict[' job '] = "ops" >>> print (one_dict) {' name ': ' Jym ' , ' age ': $, ' addr ': ' Xinjiang ', ' job ': ' Ops '} #字典的嵌套 >>> two_dict = {' name ': {' first ': ' Jy ', ' last ': ' Meng '}, ' age ' : +, ' addr ': [' sh ', ' XJ ']}>>> two_dict[' name ' [' first '] ' JY ' >>> two_dict[' addr '][0] ' sh '

   2, dictionary methods

#清空字典 >>> two_dict.clear () >>> print (two_dict) {} #删除方法一 >>> two_dict  = {' name ': {' first ': ' Jy ', ' last ': ' Meng '}, ' age ': +, ' addr ': [' sh ', ' XJ ']}>>> two_dict[' name '].pop (' first ') ' JY ' >>> print (two_dict) {' name ':  {' last ':  ' Meng '},  ' age ':  32,   ' addr ':  [' sh ',  ' XJ '} #删除方法二 >>> del two_dict[' name ' [' Last ']>>>  print (two_dict) {' name ': {},  ' age ': 32,  ' addr ':  [' sh ',  ' XJ ']} #获取字典中value >>> get_dict = two_dict.get (' Age ') >>> print (get_dict) 32# update Another dictionary through a dictionary, If the two dictionary key values are the same, then the dictionary to be updated is quasi >>> two_dict.update (one_dict) >>> print (two_dict) {' Name ':   ' Jym ',  ' age ': 24,  ' addr ':  ' Xinjiang ',  ' job ':  ' Ops '} #将字典转变为列表 (less) >> > print (two_dict) {' name ':  ' jym ',  ' age ': 24,  ' addr ':  ' Xinjiang ',  ' job ':   ' OPS '}>>> pRint (Two_dict.items ()) Dict_items ([' Name ',  ' Jym '),  (' age ',  24),  (' addr ',  ' Xinjiang '),   (' Job ',  ' Ops ')]) #取字典的values值 >>> print (Two_dict.values ()) dict_values ([' Jym ',  24,   ' Xinjiang ',  ' Ops ') #取字典的keys值 >>> print (Two_dict.keys ()) Dict_keys ([' Name ',  ' age ',   ' addr ',  ' job ']) #判断key值是否在字典中 >>>  ' name '  in two_dicttrue# takes a key value, if present, is removed, If it does not exist, add the KV value >>> print (Two_dict.setdefault (' name ')) to the dictionary jym>>> print (two_ Dict.setdefault (' name1 ', "newkv")) Newkv>>> print (two_dict) {' name ':  ' jym ',  ' age ':  24,  ' addr ':  ' Xinjiang ',  ' job ':  ' Ops ',  ' name1 ':  ' newkv '} #给定列表, remove the values from the list as key generation dictionary >>> print (Dict.fromkeys ([1,2,3,4], ' newvalue ')) {1:  ' newvalue ', 2:  ' newvalue ',  3:  ' newvalue ', 4:  ' newvalue '} #随机删除字典中的kv值 (with caution) >>> two_dict.popitem () (' name1 ' ,  ' newkv ') >>> p rint (two_dict) {' name ':  ' jym ',  ' age ': 24,  ' addr ':  ' Xinjiang ',  ' job ':  ' Ops ' }>>> two_dict.popitem () (' Job ',  ' Ops ') >>> print (two_dict) {' name ':  ' Jym ',   ' age ': 24,  ' addr ':  ' Xinjiang '}

3. Dictionary sorting

The first method # takes the key value of the dictionary out and changes it to the list store sort_list = List (Id_db.keys ()) #使用列表的方法排序sort_list. Sort () #按照顺序打印字典for key in Sort_list:print ( Key,id_db[key]) Results: C:\Python36\python36.exe c:/users/administrator/pycharmprojects/cto3/day2/ dictionary.py659001199601105413 {' name ': ' Jonny ', ' age ': +, ' addr ': ' XJ '}659001199701105413 {' name ': ' David ', ' age ': 17 ' Addr ': ' sh '}659001199801105413 {' name ': ' George ', ' age ': +, ' addr ': ' GZ '} The second method for key in sorted (id_db): Prin T (Key,id_db[key])

This article is from the "Linux Sailing" blog, make sure to keep this source http://jiayimeng.blog.51cto.com/10604001/1898498

Python Learning Diary third-dictionary