原文链接： 看示例入门 Python
📚前言
《Python 编程：从入门到实践》，入门部分（前10章）已经阅读完毕。本文通过组织罗列一些主要内容，加深一下自己对 Python 基础知识的印象。
📚结构
Python编程：从入门到实践
📚走马观花
组合课后习题，熟悉 Python 基本语法。
字符串大小写
username = "Eric"
print(username.lower())
print(username.upper())
print(username.title())
模板字符串
famous_person = "Albert Einstein"
words = "A person who never made a mistake never tried anything new."
sentence = f"{famous_person} once said, "{words}""
print(sentence)
清除字符串空白
username = "\tyi\ndong\t"
print(username)
print(username.lstrip())
print(username.rstrip())
print(username.strip())
小学生四则运算
print(5 + 3)
print(11 - 3)
print(2 * 4)
print(int(16 / 2))
列表访问与组合
sites = ['XiAn', 'BeiJing', 'NanJing', 'QingHai', 'GanShu']
print(sites[1])
print(sites[-2])
print(len(sites))
sites[1] = "GuiYang"
# 使用 sorted() 按字母顺序打印这个列表，同时不要修改它。
print(sorted(sites))
# 再次打印该列表，核实排列顺序未变。
print(sites)
# 使用 sorted() 按与字母顺序相反的顺序打印这个列表，同时不要修改它。
print(sorted(sites, reverse=True))
# 再次打印该列表，核实排列顺序未变
print(sites)
# reverse
sites.reverse()
print(sites)
# sort
sites.sort()
print(sites)
列表操作
sites = ['XiAn', 'BeiJing', 'NanJing', 'QingHai', 'GanShu']
sites.insert(0, "GuiYang")
print(sites)
print(sites.pop())
del sites[0]
sites.remove('XiAn')
print(sites)
print(len(sites))
sites[-1] = "WuHan"
print(sites)
遍历列表
pizzas = ['Seafood', 'Sausage', 'Cheese']
for pizza in pizzas:
print(f"I like {pizza} pizza.")
print('I really love pizza!')
区间与步长
odds = [value for value in range(1, 21, 2)]
for odd in odds:
print(odd ** 3)
最大值、最小值与求和
million = [value for value in range(1, 1000_000 + 1)]
print(f"min = {min(million)}")
print(f"max = {max(million)}")
print(f"sum = {sum(million)}")
列表解析
times = [value ** 3 for value in range(1, 11)]
for time in times:
print(time)
列表切片
sites = ['XiAn', 'BeiJing', 'NanJing', 'QingHai', 'GanShu']
print(f'The first three items in the list are:{sites[:3]}')
print(f'Three items from the middle of the list are:{sites[1:4]}')
print(f'The last three items in the list are:{sites[-3:]}')
列表副本
pizzas = ['Seafood', 'Sausage', 'Cheese']
friend_pizzas = pizzas[:]
元组
foods = ('Twist', 'Noodles', 'Ice Cream', 'Steamed Meat Dumpling',
'Instant Boiled Sliced Mutton')
for food in foods:
print(food)
判断语句
hello = "Hello"
world = "World"
print(hello == 'Hello')
print(hello == world)
print(hello == 'hello')
print(hello.lower() == 'hello')
score = 60
print(score < 60)
print(score == 60)
print(score > 60)
print(hello.lower() == 'hello' and score == 60)
print(hello == 'hello' or score < 60)
pizzas = ['Seafood', 'Sausage', 'Cheese']
print('seafood' in pizzas)
print('Seafood' in pizzas)
if 语句
for number in range(1, 10):
if number == 1:
print('1st')
elif number == 2:
print('2nd')
else:
print(f'{number}th')
字典
term = {
'Function': '函数',
'Variance': '变量',
'Loop': '循环',
'Network': '网络',
'Device': '设备',
'Comment': '注释',
'Keyword': '关键字',
'Primitive': '原语',
'Set': '集合',
'List': '列表',
}
print(f"Function: {term['Function']}")
print(f"Variance: {term['Variance']}")
print(f"Loop: {term['Loop']}")
print(f"Network: {term['Network']}")
print(f"Device: {term['Device']}")
for key, value in term.items():
print(f'{key}:{value}')
字典嵌套
cities = {
'XiAn': {
'country': 'China',
'population': 100000,
'fact': 'Beautiful'
},
'NewYork': {
'country': 'American',
'population': 12,
'fact': 'Modern'
},
'Kuala Lumpur': {
'country': 'Singapore',
'population': 50000,
'fact': 'Fashion'
},
}
for key, value in cities.items():
print(f'{key}:{value}')
用户输入与 while 循环
prompt = 'If you could visit one place in the world, where would you go?\n'
active = True
QUIT = 'quit'
results = []
while active:
place = input(prompt)
if place == QUIT:
break
else:
results.append(place)
print(results)
函数参数
def make_shirt(size='大号', title='I love Python'):
print(f'Size: {size}, Title: {title}')
make_shirt()
make_shirt('中号')
make_shirt("小号", "Python")
make_shirt(size='中号', title="Kotlin")
函数返回值
def make_album(name, singer, number_of_songs=None):
return {
'name': name,
'singer': singer,
'number_of_songs': number_of_songs
}
print(make_album('name1', 'singer1'))
print(make_album('name2', 'singer2'))
print(make_album('name3', 'singer3', 9))
任意数量的位置实参
def make_sandwich(*toppings):
"""打印顾客点的所有配料。"""
print(f'Sandwich: {toppings}')
make_sandwich('pepperoni')
make_sandwich('mushrooms', 'green peppers', 'extra cheese')
任意数量的关键字实参
def make_car(maker, category, **car_info):
car_info['maker'] = maker
car_info['category'] = category
return car_info
car = make_car('subaru', 'outback', color='blue', tow_package=True)
print(car)
类
class Car:
"""一次模拟汽车的简单尝试。"""
def __init__(self, make, model, year):
self.make = make
self.model = model
self.year = year
self.odometer_reading = 0
def get_descriptive_name(self):
long_name = f"{self.year} {self.make} {self.model}"
return long_name.title()
def read_odometer(self):
print(f"This car has {self.odometer_reading} miles on it.")
def update_odometer(self, mileage):
if mileage >= self.odometer_reading:
self.odometer_reading = mileage
else:
print("You can't roll back an odometer!")
def increment_odometer(self, miles):
self.odometer_reading += miles
class Battery:
"""一次模拟电动汽车电瓶的简单尝试。"""
def __init__(self, battery_size=75):
"""初始化电瓶的属性。"""
self.battery_size = battery_size
def describe_battery(self):
"""打印一条描述电瓶容量的消息。"""
print(f"This car has a {self.battery_size}-kWh battery.")
def upgrade_battery(self):
if self.battery_size != 100:
self.battery_size = 100
def get_range(self):
print(self.battery_size)
class ElectricCar(Car):
"""电动汽车的独特之处。"""
def __init__(self, make, model, year):
"""
初始化父类的属性。
再初始化电动汽车特有的属性。
"""
super().__init__(make, model, year)
self.battery = Battery()
electric_car = ElectricCar('tesla', 'model s', 2019)
electric_car.battery.get_range()
electric_car.battery.upgrade_battery()
electric_car.battery.get_range()
引入包
# https://pymotw.com/3/
from random import randint, randrange, randbytes, random, getrandbits
print(randint(1, 2))
print(randrange(1, 10000, 3))
print(randbytes(10))
print(random())
print(getrandbits(5))
读文件
file_path = 'learning_python.txt'
with open(file_path) as file_object:
content = file_object.read()
print(content)
with open(file_path) as file_object:
for line in file_object:
print(line)
with open(file_path) as file_object:
lines = file_object.readlines()
print(lines)
写文件
name = input('Pls input you name: ')
with open(file_path, 'w') as file_object:
file_object.write(name)
追加内容
reason = input('Why do you like programming: ')
with open(file_path, 'a') as file_object:
file_object.write(reason + '\n')
异常捕获
one = input('Pls input a number: ')
two = input('Pls input another number: ')
try:
number_one = int(one)
number_two = int(two)
except ValueError:
print('Pls input number')
else:
print(f'{number_one}+{number_two} = {number_one + number_two}')
文件异常
cats_file = 'cats.txt'
dogs_file = 'dogs.txt'
try:
with open(cats_file) as cats_objects:
print(cats_objects.read().rstrip())
with open(dogs_file) as dogs_objects:
print(dogs_objects.read().rstrip())
except FileNotFoundError:
pass
else:
print("Read Successfully")
json 读写
import json
def get_stored_username():
"""如果存储了用户名，就获取它。"""
filename = 'username.json'
try:
with open(filename) as f:
username = json.load(f)
except FileNotFoundError:
return None
else:
return username
def get_new_username():
"""提示用户输入用户名。"""
username = input("What is your name? ")
filename = 'username.json'
with open(filename, 'w') as f:
json.dump(username, f)
print(f"We'll remember you when you come back, {username}!")
return username
def greet_user():
"""问候用户，并指出其名字。"""
username = get_stored_username()
if username:
is_correct = input(f'Is {username} right?(yes/no)')
if is_correct == 'yes':
print(f"Welcome back, {username}!")
else:
get_new_username()
else:
get_new_username()
greet_user()
单元测试
import unittest
from employee import Employee
class EmployeeTest(unittest.TestCase):
def setUp(self) -> None:
self.default_salary = 100000
self.employee = Employee("Yi", "Dong", self.default_salary)
def test_give_default_raise(self):
self.employee.give_raise()
self.assertEqual(self.employee.salary, self.default_salary + 5000)
def test_give_custom_raise(self):
self.employee.give_raise(10000)
self.assertEqual(self.employee.salary, self.default_salary + 10000)
if __name__ == "__main__":
unittest.main()
