Python第二课

列表是什么？如何增删改查？如何排序？求表长？避免索引错误？

一、列表基本操作

关键记忆点：用[]表示列表，用逗号分割元素，列表名用复数的名称表示，打印会包含[]、访问列表元素（相当于数组名[]）+增删改依次是查找titillates[i]， 末尾添加dds.append(),   插入jjs.insert(0,"sd"),   删除del lls[0],    弹出 lls.pop(),  lls.pop(1) ,   carname.remove('j')#删除某指定的第一个值

bicycles=['trek','sd','jih',"jo"]
print(bicycles)
print(bicycles[0].title())

bicycles=['trek','sd','jih',"jo"]
print(bicycles)
print(bicycles[-1])#[-1]是最后一个元素[-2]是倒数第二个

friends_names=["lai",'a','b','c','d']
print(f'{friends_names[0]},{friends_names[1]},{friends_names[-2]}')
friends_names=["lai",'a','b','c','d']
print(friends_names[1],friends_names[-2])

friends_names=["lai",'a','b','c','d']
count=0
while count<=4:
    print(f'hello,{friends_names[count]}')
    count+=1

carname=['j','v']
print(f'i would like to own a {carname[1]}')#查找

carname=['j','v']
carname[0]='kl'
print(carname)#修改

carname=['j','v']
carname.append('jjojojo')#增加
print(carname)

carname=['j','v']
carname.insert(1,'jjojojo')#插入'jjojojo'到carname[1]处
print(carname)

carname=['j','v']
carname.insert(1,'jjojojo')
del carname[0]#删除第一个元素
print(carname)

carname=['j','v']
carname.insert(1,'jjojojo')
jj=carname.pop()#弹出栈顶元素
kk=carname.pop(0)#弹出第一个元素
print(carname)
print(jj)
print(kk)

carname=['j','v']
carname.remove('j')#删除某值
print(carname)

二、管理列表

1、使用sort()对列表进行永久排序

carname.sort()#正序

carname.sort(reverse=True)#倒序

carname=['j','v','l']
carname.sort()#正序
print(carname)
carname.sort(reverse=True)#倒序
print(carname)

2、使用sorted()对列表进行临时排序

正序和倒序

print(sorted(carname))#正序

print(sorted(carname,reverse=True))#倒序

carname.reverse()#不能放入

carname=['j','v','l',"a"]
print(sorted(carname))#正序
print(carname)

carname=['j','v','l',"a"]
print(sorted(carname,reverse=True))#倒序
print(carname)

3、反转/向打印列表

carname=['a','b','c',"d"]
print(carname)
carname.reverse()#不能放入
print(carname)
carname.reverse()
print(carname)

4、确定列表的长度

carname=['a','b','c',"d"]
print(len(carname))

5、避免索引错误

列表索引差一特性

打印出来观察

carname=['a','b','c',"d"]
print(carname[4])