Learn the summary of Python lists, dictionaries, and collections

1. List

#!/usr/bin/env python#_*_coding:utf-8_*_names = [' Alex ', ' Tenglan ', ' Eric '] #print names[0]//python2.7 no brackets print ( Names[0])

#!/usr/bin/env python#_*_coding:utf-8_*_# slices: Take multiple elements names = ["Alex", "Tenglan", "Eric", "Rain", "Tom", "Amy"]print (names[ 1:4]) #追加names. Append ("Xiao") print (names) #插入names. Insert (2, "Force insert from Eric") print (names) #修改names [2]=] the substitution "print" ( Names

#删除del names[2]print (names) #删除指定元素names. Remove ("Eric") print (names) #删除列表最后一个值names. Pop () print (names)

#扩展b = [1,2,3]names.extend (b) print (names) #拷贝name_copy =names.copy () print (name_copy) #统计names =[' Alex ', ' Tenglan ', ' Amy ', ' Tom ', ' Amy ', 1, 2, 3]print (Names.count ("Amy")) #排序names [-3] = ' 1 ' names[-2] = ' 2 ' names[-1] = ' 3 ' Names.sort () print (NA Mes

#反转names. Reverse () print (names) #获取下标print (Names.index ("Amy"))

2, meta-group

Tuples are actually similar to the list, but also to save a group of numbers, it is not once created, it can not be modified, so it is called a read-only list

Grammar

Names = ("Alex", "Jack", "Eric")

It has only 2 methods, one is count, the other is index, complete.

#!/usr/bin/env python#_*_coding:utf-8_*_names = ("Alex", "Jack", "Eric") Print (Names.count ("Alex")) print (Names.index ("Jack"))

3. String manipulation

#检测字符串是否由字母和数字组成print (' 9aA '. Isalnum ()) #是否整数print (' 9 '. IsDigit ()) #检测字符串是否只由数字组成. This method is only for unicode objects str = u "this2009" Print (Str.isnumeric ()) str = u "23443434" Print (Str.isnumeric ()) #判断字符串所包含的字符是否全部可打印. The string contains non-printable characters, such as escape characters, that return Falseprint (Str.isprintable ()) #字符串是否仅包含空格或制表符. Note: The space character is different from the blank print (Str.isspace ())

#判断字符串每个单词的首字母是否大写print (Str.istitle ())

#判断所有字母字符是否全部大写print (Str.isupper ()) # ' Alex|jack|rain ' Print ("|". Join ([' Alex ', ' Jack ', ' Rain ']) #maketransintab = "Aeiou" Outtab = "12345" Trantab = Str.maketrans (intab, outtab) str = "This is String EXAMPLE....WOW!!! " Print (Str.translate (trantab)) #out: th3s 3s str3ng 2x1mpl2....w4w!!! Print (Msg.partition (' is ')) #out: (' My Name ', ' was ', ' {name}, and age ' {age} ') #替换print ("Alex Li, Chinese name is Lijie" . replace ("Li", "Li", 1))

#大小写互换str = "This is string EXAMPLE....WOW!!!" Print (Str.swapcase ()) print (Msg.zfill (+)) # Out:00000my name is {name}, and age is {Age}print (Msg.ljust (+, "-")) #my Nam E is {name}, and age was {age}-----Print (Msg.rjust (+, "-")) #-----My name is {name}, and ' age ' {age}# detects if a string can be used as a marker, that is, whether Conforming variable naming rules b= "ddefdsdff_ haha" print (B.isidentifier ())

4. Dictionary operation

Features of the dictionary:

Dict is disordered.

Key must be unique and so is inherently heavy

#!/usr/bin/env python#-*-coding:utf-8-*-# @Time    : 2017/3/26 13:26# @Author  : corasql# @Site    : # @File    : dic.py# @Software: pycharm Community editioninfo = {    ' stu1101 ': ' Tenglan Wu ',    ' stu1102 ': ' Longze luola ',    ' s tu1103 ': "Xiaoze Maliya",} #增加info ["stu1104"] = "Python" Print (info)

#修改info [' stu1101 '] = "Test" print (info) #删除info. Pop ("stu1101") #标准删除姿势print (info) del info[' stu1103 ']  # Change position Delete print (info) #随机删除info = {' stu1102 ': ' Longze luola ', ' stu1103 ': ' Xiaoze Maliya '}info.popitem () print (info) #查找info = {' stu1102 ': ' Longze luola ', ' stu1103 ': ' Xiaoze Maliya '}print ("stu1102" in Info) #标准用法print (info.get ("stu1102"))  # Get Print (info["stu1102"]) #同上, but see below

Print (info["stu1105"])  #如果一个key不存在, error, get no, not exist only return none# loop dict# method 1for key in info:    print (Key,info[key]) # Method 2for K,v in Info.items (): #会先把dict转成list, use    print (K,V) when the data is large

5. Set operation

A collection is an unordered, non-repeating combination of data, and its main functions are as follows:

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

s = set ([3,5,9,10])      #创建一个数值集合  t = set ("Hello")         #创建一个唯一字符的集合  A = T | s          # t and S of the set  B = t & s
  
   # T and s  C = t–s          # differential Set (item in T, but not in s)  d = t ^ s          # symmetric difference set (items in t or S, but not both)
  

Basic operation:

T.add (' x ')  # Add an item  s.update ([10,37,42])  # Add multiple items in S  use remove () to delete an item:  t.remove (' H ')

Len (s) sets  the length of  x in S to  test if X is a member of S X not in S to  test if X is not a member of S  s.issubset (t)  s <= t  Test if every element in S is in T  s.issuperset (t)  s >= T  Test if every element in T is in S  s.union (t)  s | t  return Back a new set contains each element in S and T  s.intersection (t)  S & T

Returns a new set containing the common elements in S and T  s.difference (t)  s-t  Returns a new set containing elements in s but not in T  s.symmetric_difference (t) 
  s ^ t  returns a new set containing non-repeating elements in S and T  s.copy ()  returns a shallow copy of set "s"

6. File operation

#!/usr/bin/env python#-*-coding:utf-8-*-# @Time    : 2017/3/26 14:00# @Author  : corasql# @Site    : # @File 
  : file.py# @Software: pycharm Community editionf = open (' lyrics ')  # opening file First_line = F.readline () print (' first line : ', First_line)  # read a line of print (' I am the divider '). Data = F.read ()  # Read All the rest of the content, do not use print (data) when the file is large  Print file F.close ()  # Close File

7, character encoding and transcoding

Need to know:

1. In Python2 the default encoding is ASCII, the default is Unicode in Python3

2.unicode is divided into utf-32 (4 bytes), utf-16 (accounting for two bytes), Utf-8 (1-4 bytes), so utf-16 is now the most commonly used Unicode version, but in the file is still utf-8, because the UTF8 save space

3. Encode in Py3, while transcoding will also change the string to bytes type, decode decoding will also turn bytes back to string

Python2#!/usr/bin/env python#-*-coding:utf-8-*-# @Time    : 2017/3/26 13:55# @Author  : corasql# @Site    : # @Fi Le    : decode2.py# @Software: Pycharm Community editionimport sysprint (sys.getdefaultencoding ())

msg = "I love Beijing Tian ' an gate" msg_gb2312 = Msg.decode ("Utf-8"). Encode ("gb2312") GB2312_TO_GBK = Msg_gb2312.decode ("GBK"). Encode ("GBK ") print (msg) print (msg_gb2312) print (GB2312_TO_GBK) python3#!/usr/bin/env python#-*-coding:utf-8-*-# @Time    : 2017/3/26 13:51# @Author  : corasql# @Site    : # @File    : decode.py# @Software: Pycharm Community editionimport Sy Sprint (Sys.getdefaultencoding ())

msg = "I love Beijing Tian ' an gate" #msg_gb2312 = Msg.decode ("Utf-8"). Encode ("gb2312") msg_gb2312 = Msg.encode ("gb2312") #默认就是unicode, no longer decode, the great ben Gb2312_to_unicode = Msg_gb2312.decode ("gb2312") Gb2312_to_utf8 = Msg _gb2312.decode ("gb2312"). Encode ("Utf-8") print (msg) print (msg_gb2312) print (gb2312_to_unicode) print (gb2312_to_ UTF8)