Python

基础知识学习

变量和简单数据类型

字符串

修改字符串的大小写

name.title()首字母大写

name.upper()全大

name.lower()全小

在字符串中使用变量

first_name = 'ada'
last_name = 'lovelace'
full_name = f"{first_name}{last_name}"
print(full_name)

name = "alice and judy"
hobby = "like playing basketball"
full_sen. =f"{name.title()}{hobby}"
message = f"hey, do u knoe {full_sen}!"
print (message)

用f来创建消息，并赋给变量

删除空白

常用于在存储用户输入前对其进行清理

lstrip()首

rstrip()尾

strip()首尾

print("test.1")
name = "hello eric"
sent = f"{name.title()},would u like to learn some Python today?"
print(sent)

print("\n")
print("test.2")
celebrity = "albert einstein"
sentence_ce = f'{celebrity.title()} once said, "A person who never made a mistake necer tried anything new."'
print(sentence_ce)

print('\n')
print("test.3")
famous_person = 'al es'
famous_person = famous_person.title()
print(f"original:'{famous_person}'")
print(f"original:'{famous_person.lstrip()}'")
print(f"original:'{famous_person.restrip()}'")
print(f"original:'{famous_person.strip()}'")

列表

homework

names = ['sun yang','wang xinheng']
print(name[0].title())

message = f"hello, {name[0].title()}"
print(message)

commute = ['car','bicycle','motorcycle']
message_second = f"I would like to own a Honda {commute[2]}"
print(message_second)

修改添加和删除

修改

添加

append()在末尾

insert(location,'')插入

删除

无后续访问 使用del del motorcycles[0]

有后续访问 使用pop pop(0)

指定值删除 remove()

组织列表

永久排序

方法

cars.sort()

cars.sort(reverse = True)

临时排序

函数

sorted(cars)

sorted(cars,reverse = True)

倒着打印

方法

cars.reverse()

确定列表长度

函数

len(cars)

操作列表

homework

pizzas = ['meat','cheese','mushroom']
for pizza in pizzas:
	print(f"I like {pizza} pizza.")
		print(f"I like {pizza} pizza very much.")
		
print("I really love pizza")

print("\n")
animals = ['cat','dog','rabbit']
for animal in animals:
	print(f"A {animal} would make a great pet.")
	
print(" xxx")

创建数值列表

创建数字列表

numbers = list(range(1,6))

有步长

numbers = list(range(2,11,2))

计算前10个整数的平方

square = []
for value in range(1,11)
	square.append(value**2)
	
print(value)

列表解析

square = [value**2 for value in range(1,11)]
print(square)

描述性+表达式

对数字列表执行简单的统计计算

min(digits)

max(digits)

sum(digits)

使用列表的一部分

切片与遍历

players = ['hey','jude','jack','eli']
print(players[-3::2])

仍然是左闭右开

players[:4]从列表开始

players[2:]终止于列表结尾

players[-3:]最后三名队员

players[-3::2]每隔两个元素提取一个

遍历：

for player in players[:3]遍历前三名队员

复制列表

myfoods = ['pizza ','falafel','carrot cake']
friendfoods = myfoods[:]
myfoods.append('cannoli')
friendfoods.append('ice cream')

friend_foods=my_foods

两个列表关联 ，添加新元素会同时出现

元组

不可改变的列表

dimension = (200,50)

只包含一个元素的元组 dimension(200,)

If 语句

homework

message = 'hello'
message2 = 'HELLO'
if message.upper() == message2:
	print("Upper is true")
	
if message2.lower() == message:
	print("Lower is true")
	
print(message2>message)

number = [0,2,3]
number2 = [0,1,2,3]
print(number[0]==number2[0])
if 0 in number:
	print("0 in it")
else:
	print("0 not in it")

elif

处理列表

确定列表是否为空

使用多列表

current_users=['admin','jack','john','amy','lucy']
new_users=['admin','jack','HAH','QUeen','King']
#创建副本包含所有的首字母大写
new_current_users = [user.title() for user in current_users]

sequences = list(range(1,10))

字典

使用字典

访问字典中的值

alien_0 = {'color':'green','age':'1'}
print(alien_0['color'])

键-值

添加键值

直接添加

alien_0['x_position'] = 0
alien_0['y_position'] = 0

创建空键值然后添加

修改值

直接修改

alien_0['color'] = 'yellow'

删除键值对

del alien_0['points']

有类似对象组成的字典

favorite_languages = {
	'jen':'python',
	'sarah':'c',
}

language = favorite_language['sarah'].title()
print(f"She likes {language}.")

用get()来访问值

在指定的键不存在时返回一个默认值

alien_0 = {'color':'green','speed':'medium'}

point_value = alien_0.get('poionts','no point vlaue assigned')
print(point_value)

also can be:

alien_0 = {'color':'green','speed':'medium'}
message = 'no point vlaue assigned'
point_value = alien_0.get('poionts',message)
print(point_value)

遍历字典

.items()遍历所有的键值对

.keys()遍历所有的键

.values()遍历所有的值

favorite_language = {
	'jen':'python',
	'sarah':'c',
	'edward':'ruby',
	'phil':'python',
}

for name,language in favorite_languages.items():
  print(f"{name.title()}'s favorite langauge is {language.title()}")

为了剔除重复项 用set集合

for language in set(favorite_language.values):
	print(language.title())

嵌套

aliens = []

for alien_number in range(30):
	new_alien = {'color':'green','points':5,'speed':'slow'}
	aliens.append(new_alien)
	
for alien in alien[:3]:
	if alien['color'] == 'green'
		alien['color']  == 'yellow'
		
for alien in aliens[:5]:
	print(alien)

pizza = {
	'crust':'thick',
	'topping':['mushroom','extra cheese'],
}

print(f"you ordered a {pizza['crust']}-crust pizaa"
	"withfollowing toppings:")
	
for topping in pizza['toppings']:
	print("\t"+topping)

讲一个键关联到多个值的时候，可以在字典中嵌套一个列表

字典嵌套字典

users = {
	'aeinstein':{
	'first':'al',
	'last':'ein',
	'location':'princeton'
	}
	'mucrie':{
	'first':'ma',
	'last':'curie',
	'locatin':'paris'
	}
}

for username, user_info in users.items():
	print(f"{username}")
	full_name = f"{user_info['first']}{user_info['last']}
	location = user_info['location']

用户输入

message = input{"prompt:"}

int数值输入

height = input("how are u")
height = int(height)

循环

active = True

while active:
	topping = input("please input ur toppings:")
	if topping == 'quit':
		active = False
	else:
		print( )

处理列表和字典

while user:
	current_user = user.pop()
	

pets = ['dog','cat','goldfish']

while 'cat' in pets:
	pets.remove('cat')

函数

def dislay_message():
	print("I learned xxx")
	
display_message()

def make_shirt(size,message):
	printt(..)
	
make_shirt('large',message='o ')

def describe_city(city,contru='China')

describe_city('shanghai')
describe_city('hangzhou','china')

def get_fommatted_name(first_name,last_name,middle_name=''):
	if middle_name:
	fll`````
	
	return full_name.title()

middle_name=''
age=None

输入

怎么输出字典

怎么输出列表