python-Basics-Dictionary dict and set set

Dictionary

Python built-in dictionary: dict support, Dict full name dictionary, in other languages also known as map, using key-value (Key-value) storage, with a very fast search speed.

If implemented with Dict, only need a "name"-"score" of the table, directly based on the name of the results, no matter how large the table, the search speed will not be slow. Write a dict in Python as follows:

>>> stu = {' Michael ': Up, ' Bob ': $, ' Tracy ': '    #创建字典 >>> stu[' Michael ']95

Features of the dictionary:

• Dict is disordered.
• Key must be unique, so auto-weight

Basic operation of the dictionary:

• Increase
• Delete
• Modify
• Find

I. Additions and modifications

>>> info = {...     ' Stu1101 ': "Tenglan Wu",... "     stu1102 ': "Longze luola",...     ' stu1103 ': "Xiaoze Maliya",...}    #创建一个字典info >>>>>> info{' stu1103 ': ' Xiaoze maliya ', ' stu1101 ': ' Tenglan Wu ', ' stu1102 ': ' Longze luola ' }>>> info["stu1104"] = "Cang jing Empty"    #增加一个, if there is no increase in this key, otherwise modify this key >>> info{' stu1104 ': ' Cang jing empty ', ' stu1103 ': ' Xiaoze Maliya ', ' stu1101 ': ' Tenglan Wu ', ' stu1102 ': ' Longze Luola '}

Second, delete

>>> Info.pop ("stu1101")    #字典的内置方法, delete key named stu1101 ' Tenglan Wu ' >>> info{' stu1104 ': ' Cang jing empty ', ' stu1103 ' : ' Xiaoze Maliya ', ' stu1102 ': ' Longze luola '}>>> del info[' stu1103 ']    #python自带的删除方法, delete key named stu1103>> > info{' stu1104 ': ' Cang jing empty ', ' stu1102 ': ' Longze luola '}>>> info.popitem ()    #随机删除一个 (' stu1104 ', ' Cang jing empty ') > >> info{' stu1102 ': ' Longze Luola '}

Third, find

>>> ' stu1102 ' in info     #判断成员关系True >>> info.get (' stu1102 ')  #查找方法, if the lookup object does not exist, this method does not error, does not return the result ' Longze Luola ' >>> info[' stu1105 ']    #此方法查找不存在的对象会报错Traceback (most recent call last):  File "<stdin > ", Line 1, in <module>keyerror: ' stu1105 '

Iv. get all key names, values, and key-value pairs in the dictionary

>>> info = {...     ' Stu1101 ': "Tenglan Wu",... "     stu1102 ': "Longze luola",...     ' stu1103 ': "Xiaoze Maliya",...} >>>>>>>>> info.values ()    #获取值dict_values ([' Xiaoze Maliya ', ' Tenglan Wu ', ' Longze Luola ']) >>> Info.keys ()    #获取键名dict_keys ([' stu1103 ', ' stu1101 ', ' stu1102 ']) >>> info.items ()    # Get key-value pairs, return dict_items in list ([' stu1103 ', ' Xiaoze Maliya '), (' stu1101 ', ' Tenglan Wu '), (' stu1102 ', ' Longze Luola ')]

V. Methods of SetDefault

>>> Info.setdefault ("stu1106", "Alex") ' Alex ' >>> info{' stu1102 ': ' Longze luola ', ' stu1103 ': ' Xiaoze Maliya ', ' stu1106 ': ' Alex '}>>> info.setdefault ("stu1102", "deflorating la")  #因为字典中已有stu1102, and the dictionary has auto-redo function ' Longze Luola ' >>> info{' stu1102 ': ' Longze luola ', ' stu1103 ': ' Xiaoze maliya ', ' stu1106 ': ' Alex '}

Vi. Update method

>>> info{' stu1102 ': ' Longze luola ', ' stu1103 ': ' Xiaoze maliya ', ' stu1106 ': ' Alex '}>>> b = {1:2,3:4, ' Stu 1102 ":" Deflorating "}>>> info.update (b) #将字典b加入到字典info中 >>> info{' stu1102 ': ' deflorating ', 1:2, 3:4, ' stu1103 ': ' Xiaoze Maliya ', ' stu1106 ': ' Alex '}

Seven, Circular dictionary

#方法1, it is recommended to use the for key in info:    print (Key,info[key]) #方法2for k,v in Info.items (): #会先把dict转成list, do not use    print (K,V) when the data is large

Eight, multilevel nested dictionaries and dictionaries

>>> Football = {...         ' Premier League ': {...             ' Manchester United ': {...             ' Points ':,...             ' Goal ':,...         ' Rank ': 1 ...         },...             ' Arsenal ': {...             ' Points ':,...             ' Goal ':,...         ' Rank ': 4 ...         },...             ' Chelsea ': {...             ' Points ':,...             ' Goal ':,...         ' Rank ': 2 ...     }...     },...         ' Mid-super ': {...             ' Guangzhou Evergrande ': {...             ' Points ':,...             ' Goal ':,...         ' Rank ': 1 ...         },...             ' Shanghai Port ': {...             ' Points ':,...             ' Goal ': Ten,...         ' Rank ': 2 ...         },...             ' Jiangsu Suning ': {...             ' Points ':,...             ' Goal ':,...         ' Rank ': 3 ...     }...     },...         ' La Liga ': {...             ' Barca ': {...             ' Points ':,...             ' Goal ':,...         ' Rank ': 1 ...         },...             ' Real Madrid ': {...             ' Points ':,...             ' Goal ':,...         ' Rank ': 2 ...         },...             ' Horse race ': {...             ' Points ':,...             ' Goal ':,... ' Rank ': 3 ...         }...     } ... } >>>>>> football{' Medium super ': {' Jiangsu Suning ': {' rank ': 3, ' points ': 30, ' Goals ': 40}, ' Guangzhou Evergrande ': {' rank ': 1, ' points ': 45, ' Goals ': 25}, ' Shanghai Hong Kong ': {' rank ': 2, ' points ': 20, ' Goals ': 10}}, ' Premier League ': {' Manchester United ': {' rank ': 1, ' points ': 60, ' goals ': 45}, ' Arsenal ': {' rank ': 4, ' points ': 55, ' Goals ': 30}, ' Chelsea ': {' rank ': 2, ' points ': 59, ' Goals ': 40}, ' La Liga ': {' horse racing ': {' rank ': 3, ' points ': 55, ' Goals ': 58}, ' Barca ': {' rank ': 1, ' points ': 60, ' Goals ': 55}, ' Real Madrid ': { ' Rank ': 2, ' points ': 55, ' goal ': 59}}
>>> football[' Medium Super ' [' Guangzhou Evergrande ']
{' Rank ': 1, ' points ': 45, ' goal ': 25}
>>> football[' Medium Super ' [' Guangzhou Evergrande '] [' points ']
45

Collection

　　Set is similar to Dict and is a set of keys, but does not store value. Because key cannot be duplicated, there is no duplicate key in set.

The main role of the collection:

• Go to the weight, turn a list into a set, and then automatically go heavy.
• Relationship test, test the intersection of two sets of data, difference set, and the relationship between the set

Basic Operations for collections:

• Create
• Increase
• Delete

First, create

>>> Set1 = set ([1,3,4,5,99,54,22]) >>> Set2 = set ([3,22,5,6,7,10,4]) >>> set1{1, 99, 3, 4, 5, 54, 22}>>> set2{3, 4, 5, 6, 7, ten, 22}>>>>>> Set3 = set ("Hello")    #创建一个唯一字符的集合 >>> Set3 {' E ', ' l ', ' H ', ' O '}

Second, increase

>>> set1.add >>> set1{1, 3, 4, 5, 22}>>> set2.update ([10,37,42]) >>> SE T2{3, 4, 5, 6, 7, 37, 10, 42, 22}

Third, delete

>>> set1.remove (1)    #如果元素不存在, will error >>> set1{99, 3, 4, 5, 22}>>>, Set1.discard (+)    # If the element exists on the delete, does not exist then do nothing>>> set1{99, 3, 4, 5, Si, 22}>>> set1.pop ()    #使用pop () arbitrarily delete a 99>>> Set1{3, 4, 5, 22}>>> len (set1)    length of the #set 5

Iv. Collection

>>> Set1 = set ([1,3,4,5,99,54,22]) >>> Set2 = set ([3,22,5,6,7,10,4]) >>> set1{1, 99, 3, 4, 5, 54, 22}>>> set2{3, 4, 5, 6, 7, ten, a #包含set1和set2中的每一个元素, the collection (i.e. A and b) >>> set1.union (Set2) {1, 99, 3, 4, 5, 6, 7, ten, Wu, 22}>>> set3 = Set1 | Set2>>> Set3{1, 3, 4, 5, 6, 7, ten,, #包含set1和set2中相同的元素, take the intersection (that is, AB) >>> set1.intersection (Set2 {3, 4, 5, 22}>>> set3 = Set1 & set2>>> set3{3, 4, 5,} #包含set1中有但是set2中没有的元素, take the difference set (that is, A has b) &GT;&GT;&G T Set1.difference (Set2) {1, 54}>>> Set3 = set1-set2>>> Set3{1, the #包含set1和set2中不重复的元素, Symmetric difference set (that is, A has b no, B has a not) >>> set1.symmetric_difference (Set2) {1, 6, 7,, ten, 54}>>> set3 = set1 ^ SET2&GT;&G  T;> Set3{1, 6, 7, Max, ten, si} #set4是否set5的子集 >>> set4 = set ([1,2,3,4,5,6,7,8,9]) >>> set4{1, 2, 3, 4, 5, 6, 7, 8, 9}>>> set5 = set ([1,3,5,7,9]) >>> set5{1, 3, 5, 9, 7}>>> Set4.issubset (SET5) FalSe>>> Set4{1, 2, 3, 4, 5, 6, 7, 8, 9}>>> set6 = Set4 <= set5>>> set6false#set4 contains all elements of Set5 & Gt;>> Set4.issuperset (SET5) true>>> set4{1, 2, 3, 4, 5, 6, 7, 8, 9}>>> set6 = Set4 >= SET5&GT;&G T;> Set6true

V. Member Relationship Testing

>>> set7 = set ([up]) >>> set7{1, 2}>>> 1 in set7    #测试1是否是set7的成员True >>> set7 = set ([1,2,100]) >>> set7{1, 2, 100}>>> in Set7    #测试100是否不是set7的成员False

python-Basics-Dictionary dict and set set