《Python编程入门到实践》 第四章 操作列表

动手试一试
1.将三种食物存放在一个列表里，再使用for循环将每种食物打印出来

foods = ['beaf','tomato','potato']
for food in foods:
    print(food)

结果

beaf
tomato
potato

1.1 修改for循环，使其打印包含食物名称的句子，对每种食物都显示一行指定内容

foods = ['beaf','tomato','potato']
for food in foods:
    print(food.title()+"is toady's food")

结果

Beafis toady's food
Tomatois toady's food
Potatois toady's food

1.2 在程序末尾添加一行代码，它不在for循环中，指出你多喜欢美食，并包含每种食物名称和一个总结性句子

foods = ['beaf','tomato','potato']
for food in foods:
    print(food.title())
print('All I like!')

结果

Beaf
Tomato
Potato
All I like!

2.想出三种有共同特征的动物，将这些动物的名称存储在一个列表中，再使用for循环将每种动物的名称都打印出来

animals = ['pandas','pig','monkey']
for baby in animals:
    print(baby.title())

结果

Pandas
Pig
Monkey

2.1修改for循环，使每一种动物都加上同一条句子

animals = ['pandas','pig','monkey']
for baby in animals:
    print(baby.title()+' is so cute!')

结果

Pandas is so cute!
Pig is so cute!
Monkey is so cute!

2.2在程序末尾添加一行代码，指出这些动物的共同之处，如打印诸如Any of these animals would make a great pet!

animals = ['pandas','pig','monkey']
for baby in animals:
    print(baby.title()+' is so cute!')
print('Any of these animals would make a great pet!')

结果

Pandas is so cute!
Pig is so cute!
Monkey is so cute!
Any of these animals would make a great pet!

3.使用一个for循环打印数字1~20（包含）

for num in range(1,21):
    print(num)

4.创建一个列表其中包含数字1~10001，再使用一个for循环将这些数字打印出来

numlist=[]
for num in range(1,10001):
    numlist.append(num)
print(numlist)

5.计算1~10001：创建一个列表1-10001，再使用一个min()和max()核实该列表确实是从1开始到10001结束，另外用sum()计算

numlist=[]
for num in range(1,10001):
    numlist.append(num)
print(min(numlist),max(numlist),sum(numlist))

结果

1 10000 50005000

6.奇数：通过函数range（）指定第三个参数来创建一个列表，其中包含1-20的奇数，再用一个for循环将这些数字打印出来

value = list(range(1,21,2))
#print(value)
for num in value:
    print(num)

7.3的倍数：创建一个列表其中包含3-30内能被3整除的数字，再使用一个for循环将这个列表中的数字都打印出来

values = [value*3 for value in range(3,11)]
print(values)

结果：

[9, 12, 15, 18, 21, 24, 27, 30]

8.立方：将同一个数字乘三次成为立方，创建一个列表其中包含钱10个整数的立方，再用for循环将这些立方数打印出来

list = []
for value in range(1,11):
    value = value ** 3
    list.append(value)
for num in list:
    print(num)

9.立方解析：使用一个列表解析生成一个列表其中包含前10个整数的立方

values = [value**3 for value in range(1,11)]
for num in values:
    print(num)

10.切片：

list =['beaf','tomato','potato','chicken','fruits','vegetable','nooddle']
print('The first three items in the list are: '+ str(list[:3]))
print('The first three items in the list are: '+ str(list[2:5]))
print('The first three items in the list are: '+ str(list[-3:]))

结果

The first three items in the list are: ['beaf', 'tomato', 'potato']
The first three items in the list are: ['potato', 'chicken', 'fruits']
The first three items in the list are: ['fruits', 'vegetable', 'nooddle']

11.你的食物和我的食物：

mylist =['beaf','tomato','potato','chicken','fruits','vegetable']
yourlist = mylist[:]
#print(yourlist)  ['beaf', 'tomato', 'potato', 'chicken', 'fruits', 'vegetable']
mylist.append('apple')
#print(mylist) ['beaf', 'tomato', 'potato', 'chicken', 'fruits', 'vegetable', 'apple']
yourlist.append('watermelon')
#print(yourlist) ['beaf', 'tomato', 'potato', 'chicken', 'fruits', 'vegetable', 'watermelon']
print('mylist are: ')
print(mylist)
print('yourlist are: ')
print(yourlist)

结果

mylist are: 
['beaf', 'tomato', 'potato', 'chicken', 'fruits', 'vegetable', 'apple']
yourlist are: 
['beaf', 'tomato', 'potato', 'chicken', 'fruits', 'vegetable', 'watermelon']

12.使用多个循环：

mylist =['beaf','tomato','potato','chicken','fruits','vegetable']
yourlist = mylist[:]
#print(yourlist)  ['beaf', 'tomato', 'potato', 'chicken', 'fruits', 'vegetable']
mylist.append('apple')
#print(mylist) ['beaf', 'tomato', 'potato', 'chicken', 'fruits', 'vegetable', 'apple']
yourlist.append('watermelon')
#print(yourlist) ['beaf', 'tomato', 'potato', 'chicken', 'fruits', 'vegetable', 'watermelon']
for value in mylist:
    print(value)
for food in yourlist:
    print(food)

13.自助餐：
有一家自助式餐馆只提供5种简单的食物，存储元组中。
13.1使用一个for循环将该参观提供的五种食物打印出来

mylist =('beaf','tomato','potato','chicken','fruits','vegetable')
for value in mylist:
    print(value)
# beaf
# tomato
# potato
# chicken
# fruits
# vegetable

13.2尝试修改其中的一个元素，核实python会拒绝

mylist =('beaf','tomato','potato','chicken','fruits','vegetable')
mylist[2] = 'e'
print(mylist)
#TypeError: 'tuple' object does not support item assignment

13.3给元组变量赋值并使用一个for循环将新的元组的每个元素都打印出来

mylist = ('beaf','tomato','potato','chicken','fruits','vegetable')
print('original mylist: ',mylist)

mylist = ('beaf','vegetable')
print('modified mylist: ',mylist)
#original mylist:  ('beaf', 'tomato', 'potato', 'chicken', 'fruits', 'vegetable')
#modified mylist:  ('beaf', 'vegetable')

小结：
在本章我学习了如何高效地处理列表的元素；如何用for循环遍历列表，python如何根据缩进来确定程序的结构以及如何避免一些常见的缩进错误；如何创建简单的数字列表以及对数字列表执行一些操作；如何通过切片来使用列表的一部分和复制列表；学习了元组（对不应变化的值提供了一些程度的保护）