今天分享的是第四章的要点和部分课后习题的参考代码。
要点：
1、使用for遍历列表（别漏了冒号）.
2、避免缩进错误.
3、range（）的使用（range（）具有三个参数）.
4、min（）、max（）、sum（）分别用于找到数字列表的最小值、最大值和计算列表的和.
5、列表解析：列表解析将for循环和创建新元素的代码合并成一行，并自动附加新元素.
6、列表切片（参数正数和负数具有不同意义，正数表示从开头开始，负数表示从末尾开始）.个人理解列表切片可以理解成子列表.
7、切片（列表）的遍历和复制（直接用赋值号将两个列表相连，两个列表变量指向同一个列表）.
8、元组：元组元素无法修改，但是元组变量可以修改.
参考代码：
4-1
pizzas = ['pepperoni', 'onion', 'fish']
for pizza in pizzas:
print("I like " + pizza + "pizza.")
print("I really love pizza!")
运行结果：
I like pepperonipizza. I like onionpizza. I like fishpizza. [Finished in 0.0s]
4-2
animals = ["pig", "dog", "cat"]
for animal in animals:
print("A " + animal + "would make a great pet.")
print("Any of these animals has four legs")
运行结果：
A pigwould make a great pet. A dogwould make a great pet. A catwould make a great pet. Any of these animals has four legs [Finished in 0.0s]
4-3
for value in range(1,21): print(value)
4-5
values = range(1,1000001) print(min(values)) print(max(values)) print(sum(values))
运行结果：
1 1000000 500000500000 [Finished in 0.1s]
4-6
values = range(1,21,2) for value in values: print(value)运行结果：
1 3 5 7 9 11 13 15 17 19 [Finished in 0.0s]
4-7
values = range(3,31,3) for value in values: print(value)
运行结果：
3 6 9 12 15 18 21 24 27 30 [Finished in 0.0s]
4-8
cubes = [] for value in range(1,11): cube = value**3 cubes.append(cube) print(cubes)
运行结果：
[1, 8, 27, 64, 125, 216, 343, 512, 729, 1000] [Finished in 0.0s]
4-9
cubes = [value**3 for value in range(1,11)] print(cubes)
运行结果：
[1, 8, 27, 64, 125, 216, 343, 512, 729, 1000] [Finished in 0.0s]
4-10
pizzas = ['pepperoni', 'onion', 'fish', 'fruit', 'beef' ]
print("The first three items in the list are:")
print(pizzas[0:3])
print("The middle three items in the list are:")
print(pizzas[1:4])
print("The last three items in the list are:")
print(pizzas[-3:])
运行结果：
The first three items in the list are: ['pepperoni', 'onion', 'fish'] The middle three items in the list are: ['onion', 'fish', 'fruit'] The last three items in the list are: ['fish', 'fruit', 'beef'] [Finished in 0.0s]
4-11
pizzas = ['pepperoni', 'onion', 'fish', 'fruit', 'beef' ]
friend_pizzas = pizzas[:]
pizzas.append('spicy')
friend_pizzas.append('sweat')
print("My favourite pizzas are:")
for pizza in pizzas:
print(pizza)
print("My favourite pizzas are:")
for pizza in friend_pizzas:
print(pizza)
运行结果：
My favourite pizzas are: pepperoni onion fish fruit beef spicy My favourite pizzas are: pepperoni onion fish fruit beef sweat [Finished in 0.0s]
4-12 略
4-13
foods = ('tomato','potato','fish','rice','pork')
for food in foods:
print(food)
print()
foods = ('tomato','noodles','beef','rice','pork')
for food in foods:
print(food)
foods[0]='beef'
运行结果：
tomato
potato
fish
rice
pork
tomato
noodles
beef
rice
pork
Traceback (most recent call last):
File "/Users/Jhhhha/Desktop/untitled", line 12, in <module>
foods[0]='beef'
TypeError: 'tuple' object does not support item assignment
[Finished in 0.0s with exit code 1]