Python第三课——操作列表-CFANZ编程社区

总结关键记忆点：循环遍历、for循环（for ?? in ??? ：）的重复打印和只打印一次、缩进要正确、for循环后面的冒号不能忘、range(1,20,6)、range(1,6)、list(range(1,20,6))、squares.append(value**2)、

print(min(digits),max(digits),sum(digits))、squares=[value**2 for value in range(1,11)]#列表推导式

一、遍历

Python第三课——操作列表_ci

magicians=['allice','david','boba']#遍历列表中所有元素
for magician in magicians:#in后面是列表名、for后面是变量，这样就挨个输出列表中的所有元素
    print(magician)#magician和magicians的单复数命名很清晰简洁

Python第三课——操作列表_缩进_02

magicians=['allice','david','boba']
for magician in magicians:
    print(f'{magician.title()},that was a great trick!')#这里可以执行更多操作

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magicians=['allice','david','boba']
for magician in magicians:
    print(f'{magician.title()},that was a great trick!')
    print(f'i love you,{magician.title()}')#可以加很多行print（），for循环中可以加任意行代码

Python第三课——操作列表_python_04

magicians=['allice','david','boba']
for magician in magicians:
    print(f'{magician.title()},that was a great trick!')
    print(f'i love you,{magician.title()}\n')
print("thank you,everyone.")#单独成行，只执行一次则不缩进

二、缩进

1、未缩进

for magician in magicians:
print(f'{magician.title()},that was a great trick!')#未缩进错误，python会提示

2、忘记缩进额外的代码行

magicians=['allice','david','boba']
for magician in magicians:
    print(f'{magician.title()},that was a great trick!')
print(f'i love you,{magician.title()}\n')#忘记缩进这一行

3、不必要的缩进

message="l love you"
  print(message)#不必要缩进，python会提示这种错误

4、循环后不必要的缩进

magicians=['allice','david','boba']
for magician in magicians:
    print(f'{magician.title()},that was a great trick!')
    print(f'i love you,{magician.title()}\n')
    print("thank you,everyone.")#不该缩进

5、遗漏冒号

magicians=['allice','david','boba']
for magician in magicians#注意这里的冒号，python会提示
    print(f'{magician.title()},that was a great trick!')
    print(f'i love you,{magician.title()}\n')
    print("thank you,everyone.")

三、创建数值列表

for value in range(1,10):#range()函数只打印1-9，不打印最后一个数
    print(value)

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numbers=list(range(1,6))#list()将range()中的数值转换成列表
print(numbers)

Python第三课——操作列表_python_06

numbers=list(range(1,20,6))#从1开始依次加6，不能超过20
print(numbers)

Python第三课——操作列表_缩进_07

squares=[]
for value in range(1,11):
    square=value**2
    squares.append(square)#append()就是将括号里的之放入列表squares末尾中，**是value*value
print(squares)

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

digits=[1,2,3,4,5,6,7,8,9,0]
print(min(digits),max(digits),sum(digits))

squares=[value**2 for value in range(1,11)]#列表推导式
print(squares)

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等同于

squares=[]
for value in range(1,11):
    square=value**2
    squares.append(square)#append()就是将括号里的之放入列表squares末尾中，**是value*value
print(squares)

四、使用列表的一部分(切片)

players=['zhangsan','lisi','wangmazi','limei','liuxin']
print(players[0:3])

players=['zhangsan','lisi','wangmazi','limei','liuxin']
print(players[2:4])

Python第三课——操作列表_python_09

players=['zhangsan','lisi','wangmazi','limei','liuxin']
print(players[:4])#未指定索引，默认从头开始

players=['zhangsan','lisi','wangmazi','limei','liuxin']
print(players[1:])#未指定末端索引，默认访问到尾

players=['zhangsan','lisi','wangmazi','limei','liuxin']
print(players[-3:])#最后三位

Python第三课——操作列表_python_10

players=['zhangsan','lisi','wangmazi','limei','liuxin']
print(players[0:5:2])#从第一个开始每隔2个取一个,不超过4个