Python常用语法汇总(一)：字符串、列表、字典操作
1. 字符串处理
print(message.title()) #首字母大写
print(message.uper()) #全部大写
print(message.lower()) #全部小写
full_name = "lin" + "hai" #合并字符串
print("Hello, " + full_name.title() + "!")
print("John Q. %s10s" % ("Man","Public")) #%是针对字符串的格式说明符，10表示长度为10的字符，如果长度小于10则该字符串前会加入相应数量空格
print("\tPython") #制表符
print("Languages:\nPython\nC\nJavaScript")
type(12j+1) #序数尾部都有一个字母j
name = "lin hai "
name.rstrip() #删除末尾空白
name.lstrip() #删除开头空白
name.strip() #删除两端空白
age = 23
message = "Happy" + str(age) + "rd Birthday!" #str()将整数用作字符串
print(message)
2. 列表操作
shapes = ['a', 'b','c','d','e']
print(shapes[0]) #打印第1个元素
print(shapes[1].title()) #打印第2个元素，且首字母大写
print(shapes[-1]) #打印最后一个元素
print(shapes[-2]) #打印倒数第二个元素
shapes.append('granda') #添加元素
print(shapes)
e = []
e.append("e1")#添加元素
e.append("e2")
e.extend("e3","e4","e5") #同时添加多个元素
shapes.insert(0,"bb") #在第1个位置插入元素
print(shapes)
del shapes[0] #删除第一个元素
print(shapes)
poped_shapes = shapes.pop() #删除列表末尾的元素
print(shapes)
print(poped_shapes)
first_shapes = shapes.pop(0) #删除第1个元素
shapes.remove("e") #删除e, 但remove只删除第1个指定的值
print(shapes)
cars = ['bmw','audi','bench','toyota','subaru']
cars.sort() #永久性排序
print(cars)
cars.sort(reverse = True) #逆序
print(cars)
print(sorted(cars)) #临时排序
print(cars)
cars.reverse() #永久性地反转列表元素的排列顺序
len(cars) #列表的长度
for car in cars:
print(car)
for value in range(1,6): #打印1-5
print(value)
numbers = list(range(1,6))
print(numbers)
min(numbers) # 最值
max(numbers)
sum(numbers) # 求和
squares = [value**2 for value in range(1,11)] #1到10的平方
print(squares)
print(squares[0:3]) #打印0,1,2的元素
print(squares[:4]) #打印0,1,2,3的元素
print(squares[2:]) #打印从第3个元素开始到末尾的所有元素
print(squares[-3:]) #打印最后三个元素
for value in squares[:3]:
print(value)
squares1 = squares[:] #复制列表
print(squares1)
squares2 = squares #是将副本存储到squares2中，因此二者指向同一个列表
#元组：不可变的列表
dimensions = (200,50) #定义元组,使用的是圆括号而不是方括号
print(dimensions[0])
#dimensions[1] = 10 #试图修改元组是被禁止的
3. 字典操作
alient = {'color':'green','points':5} #颜色键值对和点数键值对
print(alient['color'])
print(alient['points'])
alient['x_position'] = 0 #新增键值对
alient['y_position'] = 25
print(alient)
alient['color'] = 'yellow' #修改字典中的值
del alient['points'] #删除键值对
alient1 = {} #创建空字典
alient1['color'] = 'green'
alient1['points'] = 5
#例1
user = {'username':'hy','first':'huang','last':'ying'}
for key,value in user.items(): #遍历键值对
print("\nkey:" + key)
print("value:" + value)
for item in user.keys(): #遍历键
print(item.upper())
for item in sorted(user.keys()):
print(item.upper())
for name in user.values(): #遍历值
print(name.title())
for name in set(user.values()):#用集合，使得每个元素独一无二
print(name.title())
#例2
alient_0 = {'color':'green','points':5}
alient_1 = {'color':'red','points':10}
alient_2 = {'color':'yellow','points':15}
alients = [alient_0, alient_1, alient_2] #字典列表
for alient in alients:
print(alient)
alients = []
for alient_number in range(30):
new_alient = {'color':'green','points':alient_number}
alients.append(new_alient)
for alient in alients[:5]: #显示前五个
print(alient)
print("...")
print("Total number of alients:" + str(len(alients)))
#例3
pizza = {'crust':'thick', 'toppings':['mushrooms','extra cheese']} #字典中存储列表
for topping in pizza['toppings']:
print("\t" + topping)
#例4
favorate_languages = {
'jen':['python','ruby'],
'sarah':['c'],
'edward':['ruby','go'],
'phil':['python','haskell'],
}
for name,languages in favorate_languages.items():
print("\n" + name.title() + "'s favorate languages are:")
for language in languages:
print("\t" + language.title())
#例5
users = {'aeinstein':{
'first':'albert',
'last':'einstein',
'location':'princeton',
},
'mcurie':{
'first':'marie',
'last':'curie',
'location':'paris',
},
}
for username,user_info in users.items():
print("\nUsername:" + username)
full_name = user_info['first'] + user_info['last']
location = user_info['location']
print("\tFullname" + full_name.title())
print("\tLocation:" + location.title())