《笨方法学Python》加分题32

注意一下 range 的用法。查一下 range 函数并理解它
在第 22 行(我的答案），你可以直接将 elements 赋值为 range(0, 6) ，而无需使用 for 循环？
在 python 文档中找到关于列表的内容，仔细阅读一下，除了 append 以外列表还支持哪些操作？

我的答案

32.0 基础练习

the_count = [1,2,3,4,5]
fruits = ['apples', 'oranges', 'pears', 'apricots']
change = [1, 'pennies', 2, 'dimes', 3, 'quarters']

# this first kind of for-loop goes through a list

for number in the_count:
    print(f"This is count {number}")

# same as above

for fruit in fruits:
    print(f"A fruit of type: {fruit}")

# also we can go through mixed lists too
# notice we have to use {} since we don't know what's in it

for i in change:
    print(f"I got {i}")

# we can also build lists, first start with an empty one
elements = []

#then use the range function to do 0 to 5 counts

for i in range(0,6):
    print(f"Adding {i} to the list.")
    # append is a function that lists understand
    elements.append(i)

# now we can print them out too
for i in elements:
    print(f"Element was: {i}")

#自己加的，看elements结果
print(elements)

 

 

32.1 range 的用法

最简单的变法就是查看帮助文档了，还记得我们用过的两种方法么？ 
（ ↓↓↓↓ 刮开查看 ↓↓↓↓ ） 

Python3 range() 函数返回的是一个可迭代对象（类型是对象），而不是列表类型， 所以打印的时候不会打印列表。

Python3 list() 函数是对象迭代器，可以把range()返回的可迭代对象转为一个列表，返回的变量类型为列表。

 

range(stop)
range(start, stop[, step])

创建 range 函数的实例 
range 函数会返回一个数字序列。它最多接受 3 个参数

• start：启始值（被包含），默认是 0
• stop：结束值（不包含），必填
• step：步长，默认是1，不可为0，例如：range（0， 5） 等价于 range(0, 5, 1)

>>>range(5)
range(0, 5)
>>> for i in range(5):
...     print(i)
... 
0
1
2
3
4
>>> list(range(5))
[0, 1, 2, 3, 4]
>>> list(range(0))
[]
>>>

有两个参数或三个参数的情况（第二种构造方法）：:

 

>>>list(range(0, 30, 5))
[0, 5, 10, 15, 20, 25]
>>> list(range(0, 10, 2))
[0, 2, 4, 6, 8]
>>> list(range(0, -10, -1))
[0, -1, -2, -3, -4, -5, -6, -7, -8, -9]
>>> list(range(1, 0))
[]
>>>
>>>

 

 

32.2 不使用 for-loop ，直接为 elements 赋值为 range(6)

 

the_count = [1,2,3,4,5]
fruits = ['apples', 'oranges', 'pears', 'apricots']
change = [1, 'pennies', 2, 'dimes', 3, 'quarters']

# this first kind of for-loop goes through a list

for number in the_count:
    print(f"This is count {number}")

# same as above

for fruit in fruits:
    print(f"A fruit of type: {fruit}")

# also we can go through mixed lists too
# notice we have to use {} since we don't know what's in it

for i in change:
    print(f"I got {i}")

# we can also build lists, first start with an empty one
elements = []

#then use the range function to do 0 to 5 counts

elements = list(range(0,6))

# now we can print them out too
for i in elements:
    print(f"Element was: {i}")

#自己加的，看elements结果
print(elements)

 

需要为range(0,6)加上list才是需要的elements列表