python基础（三）

操作列表

• 遍历整个列表
  

• 避免缩进错误
  

• 创建数值列表
  

• 使用列表的一部分
  

• 元组
  

• 设置代码格式

littles = ['q','w','e','m']
for little in littles:
    print(little) #for循环

q
w

e
m

#在for循环中执行更多的操作
for little in littles:
    print(little.title() + ",hahahhaha!")

Q,hahahhaha!

W,hahahhaha!
E,hahahhaha!
M,hahahhaha!

for little in littles:
    print(little.title() + ",hahahhaha!")
    print("I love my home!" + "
")#两条for循环都缩进了，都将针对每个字母执行一次

Q,hahahhaha!
I love my home!

W,hahahhaha!
I love my home!

E,hahahhaha!
I love my home!

M,hahahhaha!
I love my home!

for  little in littles:
    print(little.title() + ",hahahhaha!")
print("I love my home!")#最后执行一次

Q,hahahhaha!
W,hahahhaha!
E,hahahhaha!
M,hahahhaha!
I love my home!

for little in littles:
    print(little.title() + ",hahahhaha!")
    print("I love my home!" + "
")
print("hihihi!")

Q,hahahhaha!

I love my home!

W,hahahhaha!
I love my home!

E,hahahhaha!
I love my home!

M,hahahhaha!
I love my home!

hihihi!

#创建数值列表

#使用函数range()
for value in range(1,5):
    print(value)

1

2
3

4

number = list(range(1,5))
print(number)

[1, 2, 3, 4]

even_numbers = list(range(2,11,2))
print(even_numbers)

[2, 4, 6, 8, 10]

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

[1, 4, 9, 16, 25, 36, 49, 64, 81, 100]

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

[1, 4, 9, 16, 25, 36, 49, 64, 81, 100]

#对数字列表进行简单的统计计算
digits = range(0,10)
min(digits)

0

max(digits)

9

sum(digits)

45

这个用起来比较方便！for循环直接放在里面

#列表解析，简化代码
squares = [value**2 for value in range(1,11)]
print(squares)

[1, 4, 9, 16, 25, 36, 49, 64, 81, 100]

#使用列表的一部分

切片，左闭右开

haha = ['99','96','97','66']
print(haha[0:3])

['99', '96', '97']

print(haha[1:4])

['96', '97', '66']

print(haha[:4])

['99', '96', '97', '66']

print(haha[2:])

['97', '66']

print(haha[-3:])#最后三个

['96', '97', '66']

haha = ['99','96','97','66']
print("Here are the scores:")
for score in haha[:3]:
    print(score.title())

Here are the scores:

99
96
97

#复制列表，可创建一个包含整个列表的切片
haha = ['99','96','97','66']
hihi = haha[:]
print("my scores are:")
print(haha)

my scores are:

['99', '96', '97', '66']

print("his scores are:")

print(hihi)

his scores are:
['99', '96', '97', '66']

haha.append('100')
hihi.append('99')
print(haha)
print(hihi)

['99', '96', '97', '66', '100']

['99', '96', '97', '66', '99']

#元组

列表非常适合于存储在程序运行期间可能变化的数据集，列表是可以修改的。[]

元组，适用于创建一系列不可修改的元素。（）

dim = (200,50)
print(dim[0])

200

print(dim[1])

50

dim[0] = 100
print(dim[0])#python不能给元组的元素赋值

---------------------------------------------------------------------------

TypeError                                 Traceback (most recent call last)
<ipython-input-57-743659d5cfb2> in <module>
----> 1 dim[0] = 100
      2 print(dim[0])

TypeError: 'tuple' object does not support item assignment

#遍历元组中的所有值
dims = (200,50)
for dim in dims:
    print(dim)

200
50

#修改元组变量，重新定义整个元组
dims = (400, 100)
print(dims)

(400, 100)

for dim in dims:
    print(dim)

400

100