python入门

基于python3.8.2版本

一、语法

#!/usr/bin/env python3
# -*- coding: utf-8 -*-

'a test module'

__author__ = 'authorName'


def fn(x):
    return x*x

r = map(fn, [1,2,3,4,5,6])

print(list(r))    

from functools import reduce

def fn2(x, y):
    return x*10 + y
ss = reduce(fn2, [1,2,3,4,5])
print(ss)

a = ['adam', 'LISA', 'barT']
def f1(x):
    return x[0].upper() + x[1:].lower()
aa = map(f1, a)
print(list(aa))

def f2(x, y):
    return x * y

ff2 = reduce(f2, [1,2,3])    
ff3 = reduce(lambda x,y:x*10+y ,[1,2,3])
print(ff2,':',ff3)

def ff4(x,y):
    return x/10 + y
    
ff4a=reduce(ff4, [1,2,3])
print('ff4a:',ff4a)

#字符串转浮点
def strtofloat(s):
    i = s.find('.')
    digist = {'0':0, '1':1, '2':2, '3':3, '4':4, '5':5, '6':6, '7':7, '8':8, '9':9}
    def f1(x,y):
        return x*10+y
    def f2(n):
        return digist[n]
    def f3(x,y):
        return x/10+y
    return reduce(f1, map(f2,s[:i])) + reduce(f3, map(f2, s[:i:-1]))/10
print('123.456:', strtofloat('123.456'))


def f1(x):
    return x%2==0
xx = filter(f1, [1,2,3,4,5,6])
print(list(xx))

aa=sorted(['a','AA','sdf'],key=str.lower,reverse=True)
print(aa)

L = [('Bob', 75), ('Adam', 92), ('Bart', 66), ('Lisa', 88)]
def sortByName(x):
    return x[0]
def sortByCords(x):
    return x[1]
ll = sorted(L,key=sortByName)
ss = sorted(L, key=sortByCords, reverse=True)
print("ll by name:", ll,";ss:",ss)

def fn(*args):
    return args
    
def addCount():
    n=0
    def add():
        nonlocal n
        n = n + 1
        return n
    return add
ff=addCount()
print('ff:',ff(),ff(),ff())


def addCount():
    n=[0]
    def add():
        n[0] = n[0] + 1
        return n[0]
    return add
ff=addCount()
print('ff:',ff(),ff(),ff())

def addCount():
    global n
    n=0
    def add():
        global n
        n = n + 1
        return n
    return add
ff=addCount()
print('ff:',ff(),ff(),ff())

xx = map(lambda x: x*x, [1,2,3])
print('xx:',list(xx))
        
f = lambda x:x+x
print('ff:',f(1))

L = list(filter(lambda n: n%2==1, range(1, 20)))
print(L)
    
print(addCount.__name__)
int('123', base=8)

#装饰器decorator
def log(func):
    def wrapper(*args, **kw):
        print('log call %s()' %func.__name__)
        return func(*args, **kw)
    return wrapper
    
@log
def now():
    print("exec now")
    
now()

import sys
if __name__ == "__main__":
    print(sys.argv, __doc__)
    
class Student(object):
    def __init__(self, name, score):
        self.__name = name
        self.__score = score
    def print_score(self):
        print("%s: %s" %(self.__name, self.__score))
    def get_name(self):
        return self.__name
    def get_score(self):
        return self.__score
    def set_score(self, score):
        self.__score = score

aa = Student('aa',100)
aa.print_score()
print('get_name: %s' % aa.get_name())
        
class Animal(object):
    count = 0
    __slots__=('name','age')
    def __init__(self):
        Animal.count = Animal.count + 1
        print('init Animal')
    def run(self):
        print('animal running...')
class Dog(Animal):
    def __init__(self):
        print('init Dog')
animal = Animal()
animal.run()
dog = Dog()
dog.run()
print(isinstance(dog, Dog))
print(isinstance(dog, Animal))

dir(dog) #获得一个对象的所有属性和方法

hasattr(dog,'run')
getattr(dog,'aa','test')

print(Animal.count)


class Student(object):
    
    @property  #Python内置的@property装饰器就是负责把一个方法变成属性调用的,把一个getter方法变成属性，只需要加上@property就可以了，此时，@property本身又创建了另一个装饰器@birth.setter，负责把一个setter方法变成属性赋值
    def birth(self):
        return self.__birth
    @birth.setter    
    def birth(self,value):
        self.__birth = value
        
    @property
    def age(self):
        return self.__birth -10
        
a = Student()
a.birth=100

print('a.birth: %s' %a.birth)

# a.age=100
print('a.age: %s' %a.age)

class Screen(object):
    def __init__(self, width, height):
        self.__width = width
        self.__height = height
    
    @property
    def width(self):
        return self.__width
        
    @width.setter
    def width(self, width):
        self.__width = width
        
    @property
    def height(self):
        return self.__height
        
    @width.setter
    def height(self, height):
        self.__height = height
        
    @property
    def resolution(self):
        return self.__width * self.__height
        
screen = Screen(100,200)
print('%s' %screen.width)
screen.width=300
print('%s' %screen.width)

print('resolution:%s' %screen.resolution)

class RunMixin(object):
    def runx(self):
        print(' xxx running...')
class Test(Animal, RunMixin): #多重继承，多个类存在同一个方法，会取主继承类的方法
    def aa(self):
        print('running...')
test = Test()
test.runx()

from enum import Enum, unique

@unique
class Weekday(Enum):
    Sun = 0
    Mon = 1
    Tue = 2
    Wed = 3
    Thu = 4
    Fri = 5
    Sat = 6
    
print('Weekday.Sun %s' %Weekday.Sun)

def fn(self, name='world'):
    print('Hello, %s.' %name)
    
Hello = type('Hello', (object,), dict(hello=fn))     #动态创建一个class对象，type()函数依次传入3个参数：1.class的名称；2.继承的父类集合，注意Python支持多重继承，如果只有一个父类，别忘了tuple的单元素写法；3.class的方法名称与函数绑定，这里我们把函数fn绑定到方法名hello上。
h = Hello()
h.hello()

import logging
try:
    print('try...')
    r = 10 / int('a')
    print('result:',r)
except ValueError as e:
    print('ValueError',e)
    logging.exception(e)
except ZeroDivisionError as e:
    print('ZeroDivisionError', e)
finally:
    print('finally')
print('end')

def foo(s):
    n = int(s)
    if n==0:
        raise ValueError('invalid value:%s' %s) #抛出ValueError
    return 10/n
def bar():
    try:
        foo(0)
    except ValueError as e:
        print('ValueError')
        raise #raise语句如果不带参数，就会把当前错误原样抛出,继续往上抛，让顶层调用者去处理
        
bar()

二、语法

age = 20
if age >= 18:
    print("your age is :", age)
    print("adult")
elif age < 10:
    print('yong')
else:
    print('other')
    
arr = ['a', 'b', 'c']
for i in arr:
    print("arr item:", i)
    
sum = 0
for i in range(101):
    sum = sum + i
print("range item:", sum)

n = 30
i = 0
while i < 10:
    i = i + 1
    print("i:",i)
    
birther = 2000#input("your brith:")
s = int(birther)
if s > 2000:
    print('20后')
    print('test')
else:
    print('other')
    
def absfn(x):
    if (x > 3):
        return x
    else:
        return x+x
        
print("absfn:",absfn(3))

from collections import Iterable
print('iterable:', isinstance('abc', Iterable))

import os 
dirtest = [d for d in os.listdir('../')]
print('dirtest:', dirtest)

l = ['AB','BC','EF']
ll = [s.lower() for s in l]
print(ll)

L = ['Hello', 'World', 18, 'Apple', None]
LL = [l.lower() if isinstance(l, str) else l for l in L]
LLL= [l.lower() for l in L if isinstance(l,str)]
print('LL:', LL,';LLL:', LLL)

三、语法

import re
test = re.match(r'^(d{2})-(d{3})', '12-345')
print(test,test.group(0),test.group(1),test.group(2))
print(test.groups())


from datetime import datetime
print(datetime.now())
print(datetime.now().strftime('%a, %b %d %H:%M')) #datetime转str

dt = datetime(2020,3,1,12,10)
print(dt.timestamp()) #单位秒，timestamp是一个浮点数，它没有时区的概念，而datetime是有时区的
print(datetime.fromtimestamp(dt.timestamp())) #转换为datetime

cday = datetime.strptime('2015-6-1 18:19:59', '%Y-%m-%d %H:%M:%S') #字符串转datetime
print(cday)

四、语法

f = open('./test.py', 'r', encoding='UTF-8')
x=f.read();
f.close();
print(x)

f = open('./test.py', 'a', encoding='UTF-8')
f.write('#test test test open ')
f.close();

f = open('./test.py', 'r', encoding='UTF-8', errors='ignore')
x=f.read()
f.close()
print('write:%s' %x)


with open('./test.py', 'r', encoding='UTF-8') as f:
    print(f.read())
    
with open(r'D:xxxpython	est.py', 'r', encoding='UTF-8') as f: #在路径前面加r，即保持字符原始值的意思。
    print(f.read())
    
from io import StringIO    
f = StringIO()
f.write('hello')
f.write(' ')
f.write('wrold!')

print(f.getvalue())

import os
os.environ.get('PATH') #要获取某个环境变量的值
s = os.path.abspath('.') # 查看当前目录的绝对路径
testdir = os.path.join(s, 'testdir') #使用join创建新目录路径
if os.path.exists(testdir) == False: #存在文件或目录
    os.mkdir(testdir) #创建新目录

ll=[x for x in os.listdir('.') if os.path.isdir(x)] #列出当前目录下的所有目录
print(ll)

import json
d = dict(name='foo',age=123)
dstr= json.dumps(d)#json转字符串
print(dstr) 

dd = json.loads(dstr) #字符串转json
print(dd)


import re

test = '_abc'
if re.match(r'^d', test):
    print('matched')
else:
    print('not matched')
    
print(re.split(r's+', 'a b   c d   e'))

from collections import namedtuple
Point = namedtuple("Point",['x','y'])
p = Point(0,1)
print(p.x, p.y)

import hashlib
md5=hashlib.md5()
md5.update('this is md5 test '.encode('UTF-8'))
md5.update('add'.encode('UTF-8')) #如果数据量很大，可以分块多次调用update()，最后计算的结果和一次调用所有数据是一样的
print(md5.hexdigest())

def get_md5(s):
    return hashlib.md5(s.encode('UTF-8')).hexdigest()
print(get_md5('test'), get_md5('this is md5 test add'))


import hmac
message=b'hello'
key=b'secret'
h = hmac.new(key, message, digestmod='MD5') #支持MD5和SHA-1
print(h.hexdigest())


from urllib import request, parse

with request.urlopen('https://www.qq.com/') as f:
    data = f.read()
    print('status:',f.status, f.reason)
    for k, v in f.getheaders():
        print('%s: %s' %(k, v))
   # print('data:',data.decode('UTF-8'))

req = request.Request('https://www.qq.com/')
req.add_header('user-agent', 'Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/79.0.3945.88 Safari/537.36') #添加header

with request.urlopen(req) as f:
    data = f.read()
    print('status:',f.status, f.reason)
    for k, v in f.getheaders():
        print('%s: %s' %(k, v))
    print('data:',data.decode('UTF-8'))
    

#postData = parse.urlencode([
#    ('name', 'test'),
#    ('age', 20)
#])    
#req = request.Request('https://www.qq.com/')
#req.add_header('Origin', 'https://www.qq.com')
#with request.urlopen(req, data=postData.encode('UTF-8')) as f:  #post请求，只需要把参数data以bytes形式传入
#    data = f.read()
#    print('status:',f.status, f.reason)
#    for k, v in f.getheaders():
#        print('%s: %s' %(k, v))
#    print('data:',data.decode('UTF-8'))

from html.parser import HTMLParser

class MyHTMLParser(HTMLParser):
    def __init__(self):
        super().__init__()
        self.content = ""
    def handle_starttag(self, tag, attrs):
        print('handle_starttag:','<%s>' % tag)
        if tag == 'meta' and ('name', 'description') in attrs:
            print('attrs:',attrs[1][0], attrs[1][1])
            self.content = attrs[1][1]
    def handle_endtag(self, tag):
        print('handle_endtag:','</%s>' % tag)

    def handle_startendtag(self, tag, attrs):
        print('handle_startendtag:','<%s/>' % tag)

    def handle_data(self, data):
        print('data:',data)

    def handle_comment(self, data):
        print('<!--', data, '-->')

    def handle_entityref(self, name):
        print('&%s;' % name)

    def handle_charref(self, name):
        print('&#%s;' % name)
        
myHtmlParser = MyHTMLParser()
myHtmlParser.feed('''<html>
<head></head>
<body>
<!-- test html parser -->
    <p>Some <a href="#">html</a> HTML&nbsp;tutorial...<br>END</p>
</body></html>''')
myHtmlParser.feed(data.decode('UTF-8'))
print('page title is: %s' %myHtmlParser.content)


# 导入turtle包的所有内容:
from turtle import *

# 设置笔刷宽度:
width(4)

# 前进:
forward(200)
# 右转90度:
right(90)

# 笔刷颜色:
pencolor('red')
forward(100)
right(90)

pencolor('green')
forward(200)
right(90)

pencolor('blue')
forward(100)
right(90)

# 调用done()使得窗口等待被关闭，否则将立刻关闭窗口:
done()

参考文档：https://www.liaoxuefeng.com/wiki/1016959663602400/1016959856222624