刚接触Python3版本的小伙伴们，编程时会对于Python中各种数据结构如：array、list、dict、set以及字符串str操作都不太熟悉。同时类似于Python网络编程、文件读取、数据库连接以及协程这些编程模板基本也都是固定的，本文便就这些方面进行总结，希望让大家进行Python3编程时能够更加的便捷，可以直接复制粘贴而不用每次都手敲了，好下面进入正题啦！

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一、list各种操作

1、list和array之间相互转换及遍历

#!/usr/bin/env python3# -*- coding: utf-8 -*-from numpy import *#python 中list和array之间的相互转换以及list和array的遍历testList=[[1,2,3],[4,5,6]]#将list转化成arraytestArray=array(testList)for i in range(testArray.shape[0]): for j in range(testArray.shape[1]): print(testArray[i,j],' ',end='') print()print()#将array转化成listtoList=testArray.tolist()for i in range(len(toList)): for word in toList[i]: print(word,' ',end='') print()

2、查找返回list中出现次数最多的那个元素

#!/usr/bin/env python3# -*- coding: utf-8 -*-#查询list中出现次数最多的元素def top(list): s=set(list) d={} for i in s: d[i]=list.count(i) print('下面输出的是前k个字典：',end='') print(d) list1=[] for i in d.values(): list1.append(i) ma=max(list1) key_max=get_keys(d,ma) string=key_max[0] return string#get_keys实现已知dict的value返回keydef get_keys(d,value): return [k for k,v in d.items() if v==value]if __name__ == '__main__': listTest=[1,1,1,2,2,3,4,5,5,6,6,6,6,6,7] s=top(listTest) print('出现次数最多的元素: ', s)

二、array各种操作

1、Python3中如何自定义结构化数组

#!/usr/bin/env python3# -*- coding: utf-8 -*-from numpy import *import pandas as pd#通过下面这种方式定义结构数组,自定义结构数组dtypes={'name':'s32','age':'i','weight':'f'}mydata=pd.DataFrame([['zhang',32,65.5],['wang',24,55.2]],columns=['name','age','weight'])print(mydata)t=mydata.shapefor i in mydata.columns: print('') for j in range(mydata.ndim): print(' '+str(mydata[i][j]),end='')

2、array切片操作

#!/usr/bin/env python3# -*- coding: utf-8 -*-from numpy import *a=arange(10)**3for element in a.flat: print(' %d' %element,end='')print('')for i in range(a.size): print(' %d' %a[i],end='')print('')print(a[2:5]) #数组的切片处理a[:6:2]=-1000 #省略的位置代表0print(a)m=a[: :-1] #将一维数组反转print(m)

三、dict各种操作

1、如何根据dict字典的value反去除key

def get_keys(d,value): return [k for k,v in d.items() if v==value]

2、dict中存取key、value各种函数使用

#!/usr/bin/env python3# -*- coding: utf-8 -*-import operatora_dict={1:{'name':'Mary'},2:'python',3:'google','email':'qq.com'}print(a_dict)print(a_dict.items())#字典的三个函数 keys()、values()、items()print(a_dict.keys())print(a_dict.values())print(a_dict.items())#两种遍历dict中key的方式for k in a_dict.keys(): print(k)for k in a_dict: print(k)print()#两种遍历dict中value的方式for v in a_dict.values(): print(v)for k in a_dict.keys(): print(a_dict[k])print()#Python字典调用items()函数以列表返回可遍历的(键，值)元组数组for k,v in a_dict.items(): print(str(k)+' : '+str(v))for k in a_dict: print(str(k)+' : '+str(a_dict[k]))print()#get函数的使用，用来取出dict的value的for k in a_dict.keys(): print(a_dict.get(k))print('字典的存储的数据量为: %d' %len(a_dict))

四、set各种操作

1、set声明操作集合和list之间转化

import numpy as npimport operator#set中只存储key,不存储value，并且key不能够重复#下面给出Python中声明set的方法s1=set([])while len(s1)!=5: a=np.random.randint(0,10) s1.add(a)print(s1)s2=set([])for i in range(10): s2.add(i)print(s2)#两个set进行相减操作s3=s2-s1print(s3)#将set转化成listlist1=list(s1)list2=list(s3)for i in range(len(list1)): print(list1[i])for j in range(len(list2)): print(list2[j])

五、字符串操作

1、Python中字符串相等判断

str1='csdn'str2='csdn'#Python中和Java不同，字符串相等直接使用‘==’if str1==str2: print('相等')else: print('不相等')

2、将文本中有效单词取出，过滤掉空格和其他符号

#!/usr/bin/env python3# -*- coding: utf-8 -*-import re#在表示完整的文件路径需要在前面加 r file_name = r'E:\python\Python_project\machine learning\bayes\email\ham\23.txt'lines_count = 0words_count = 0chars_count = 0words_dict = {}lines_list = []with open(file_name, 'r') as f: print(f) for line in f: #print('line: ',line) lines_count = lines_count + 1 chars_count = chars_count + len(line) #这里的findall函数特殊 match = re.findall(r'[^a-zA-Z0-9]+', line) #print('match: ',match) for i in match: # 只要英文单词，删掉其他字符 line = line.replace(i, ' ') #split()返回的是 list lines_list = line.split() #下面的i表示的是单词，所以字典的key是单词，value是单词出现的次数 for i in lines_list: if i not in words_dict: words_dict[i] = 1 else: words_dict[i] = words_dict[i] + 1print('words_count is %d' %len(words_dict))print('lines_count is %d' %lines_count)print('chars_count is %d' %chars_count)print(words_dict.keys())print(words_dict.values())for k,v in words_dict.items(): print(k,v)

六、json使用

1、Python对象和json对象相互转化

#!/usr/bin/env python3# -*- coding: utf-8 -*-import json#python对象--->json对象 json.dumps(python对象)#Python对象

2、利用一个函数定制json序列化

#!/usr/bin/env python3# -*- coding: utf-8 -*-import json#Python中类对象json对象#利用一个函数定制json序列化class Student(object): def __init__(self, name, age, score): self.name = name self.age = age self.score = score def __str__(self): return 'Student object (%s, %s, %s)' % (self.name, self.age, self.score)s = Student('Bob', 20, 88)std_data = json.dumps(s, default=lambda obj: obj.__dict__)print('Dump Student:', std_data)rebuild = json.loads(std_data, object_hook=lambda d: Student(d['name'], d['age'], d['score']))print(rebuild)

七、读取文件操作

1、一次性读取所有文件内容到内存：read()

#!/usr/bin/env python3# -*- coding: utf-8 -*-from datetime import datetime#read函数对于文件过大时，会导致内存爆炸的！with open('test1.txt','r') as f: s=f.read() print('open for read') print(s)

2、每次读取一行文件内容：readline()

l=[]try: f=open('test2_data.txt','r') s=f.readline() #每次读取一行文件内容，循环读取 while len(s)!=0: list1=[] list1=s.split('\t') #将读取的文件内容保存到list中 l.append(list1) s=f.readline() #print(l)except: if f: f.close()

3、一次性读取所有文件内容但是按行返回list：readlines() 很好用

f=open('testSet.txt') for line in f.readlines(): lineList=line.strip().split() print(lineList)

4、向文件中写信息

#!/usr/bin/env python3# -*- coding: utf-8 -*-from datetime import datetimewith open('test.txt', 'w') as f: f.write('今天是 ') f.write(datetime.now().strftime('%Y-%m-%d'))

八、数据库操作

1、Python数据库的连接模板

#!/usr/bin/env python3# -*- coding: utf-8 -*-#导入mysql驱动import mysql.connector#连接mysql数据库conn=mysql.connector.connect(user='root',password='',db='test')cur=conn.cursor()#查询多条记录info=cur.fetchmany(5)for ii in info: print(ii)#运行查询的另一种方式cur.execute("select * from user")values=cur.fetchall()print(values)#提交事务conn.commit()conn.close()cur.close()

九、TCP网络通讯

1、服务器端server

#!/usr/bin/env python3# -*- coding: utf-8 -*-import socket,threading,timedef tcplink(socket,addr): print('Accept new connection from %s:%s...' %addr) sock.send(b'Welcome!') while True: data=sock.recv(1024) time.sleep(1) if not data or data.decode('utf-8')=='exit': break sock.send(('Hello,%s!' % data.decode('utf-8')).encode('utf-8')) sock.close() print('Connection from %s:%s closed' %addr)if __name__=='__main__': # 创建一个socket: s = socket.socket(socket.AF_INET, socket.SOCK_STREAM) #监听窗口 #其中IP地址和端口号使用tuple的形式 s.bind(('127.0.0.1',9999)) #开始监听端口 s.listen(5) print('waiting for connection...') #永久循环接受客服端连接 while True: #接受一个新连接 sock,addr=s.accept() #创建新线程处理TCP连接 t = threading.Thread(target=tcplink, args=(sock, addr)) t.start()

2、客服端client

#!/usr/bin/env python3# -*- coding: utf-8 -*-import socket# 创建一个socket:s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)#建立连接s.connect(('127.0.0.1',9999))#接受欢迎消息print(s.recv(1024).decode('utf-8'))for data in [b'Michael',b'Tracy',b'Sarah']: s.send(data) print(s.recv(1024).decode('utf-8'))s.send(b'exit')s.close()

十、Python协程async

1、Python中协程比使用多线程更高效

如是Python3.5及以上版本，代码如下：

#!/usr/bin/env python3# -*- coding: utf-8 -*-import asyncioasync def wget(host): print('wget %s...' % host) connect = asyncio.open_connection(host, 80) reader,writer=await connect header = 'GET / HTTP/1.0\r\nHost: %s\r\n\r\n' % host writer.write(header.encode('utf-8')) await writer.drain() while True: line=await reader.readline() if line== b'\r\n': break print('%s header > %s' % (host, line.decode('utf-8').rstrip())) writer.close()loop = asyncio.get_event_loop()tasks = [wget(host) for host in ['www.sina.com.cn', 'www.sohu.com', 'www.163.com']]loop.run_until_complete(asyncio.wait(tasks))loop.close()

如果是Python3.4的版本，代码如下：

#!/usr/bin/env python3# -*- coding: utf-8 -*-import [email protected] wget(host): print('wget %s...' % host) connect = asyncio.open_connection(host, 80) reader, writer = yield from connect header = 'GET / HTTP/1.0\r\nHost: %s\r\n\r\n' % host writer.write(header.encode('utf-8')) yield from writer.drain() while True: line = yield from reader.readline() if line == b'\r\n': break print('%s header > %s' % (host, line.decode('utf-8').rstrip())) # Ignore the body, close the socket writer.close()loop = asyncio.get_event_loop()tasks = [wget(host) for host in ['www.sina.com.cn', 'www.sohu.com', 'www.163.com']]loop.run_until_complete(asyncio.wait(tasks))loop.close()

以上内容便是Python3.x常用数据结构和常用模板的总结，当然并不可能很全啦，后期如果有比较好的模板还会继续更新，小伙伴们如果有比较好的模板也欢迎添加分享！