python学习——python编程：从入门到实践（第4章）

4.4第四章操作列表

4.1 遍历整个列表

eg1：for循环打印
names= ["li","wu","zhu","zhang","wang"]
for name in names:
    print(name)

li
wu
zhu
zhang
wang

eg2：for循环中，一次循环完成后，在重新执行直至循环结束

names= ["li","wu","zhu","zhang","wang"]
for name in names:
    print(name.title() + ", nice to meet you!")
    print("Good morning!" + name.title()+".\n")

names= ["li","wu","zhu","zhang","wang"]
for name in names:
    print(name.title() + ", nice to meet you!")
    print("Good morning!" + name.title()+".\n")
print("welcome!")

for number in range(1,5):   ……………………………………………………………………range（1，5）左闭右开，只能生成1：4的数字
    print(number)         

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

[1, 2, 3, 4]

eg6：还可以指定步长，相当于等差数列中的公差（range（首项，尾项，公差））

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

[2, 4, 6, 8, 10]

eg7：数的平方（**）

squares = []……………………………………………………空列表
for value in range(1,11):
    squares.append(value**2)……………………………………列表末尾开始循环添加元素
print(squares)

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

eg8：
numbers =[1,5,6,3,7,89,44,55,687]
print(min(numbers))
print(max(numbers))
print(sum(numbers))

eg9：
squares = [value**2 for value in range(1,11)] …………………………………………for句尾无冒号
print(squares)

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

eg10：
names= ["li","wu","zhu","zhang","wang"]
print(names[1:4]) ………………………………………………………………………………………………索引从1开始，左开右闭，所以列表最后一位索引是3

[‘li‘, ‘wu‘, ‘zhu‘]

names= ["li","wu","zhu","zhang","wang"]
print(names[:3])………………………………………………………………………………若没有指定列表第一个索引，python自动从头开始提取

[‘wu‘, ‘zhu‘, ‘zhang‘]

names= ["li","wu","zhu","zhang","wang"]
print(names[1:])……………………………………………………………………………………省略终止索引，python提取到列表的末尾

eg13：
names= ["li","wu","zhu","zhang","wang"]
print(names[-3:])…………………………………………………………………………………………负数索引返回离列表末尾相应距离的元素

[‘zhu‘, ‘zhang‘, ‘wang‘]

eg14：
names= ["li","wu","zhu","zhang","wang"]
print(names[:-3])

[‘li‘, ‘wu‘]

4.3.2遍历切片

eg15：

names= ["li","wu","zhu","zhang","wang"]
print("Here are my friends:")
for friend in names[:4]:
     print(friend)

Here are my friends:
li
wu
zhu
zhang

4.3.3复制列表

eg16：
names= ["li","wu","zhu","zhang","wang"]
friends = names[:]

print("There are competitors:")
print(names)
print("My friends:")
print(friends)

There are competitors:
[‘li‘, ‘wu‘, ‘zhu‘, ‘zhang‘, ‘wang‘]
My friends:
[‘li‘, ‘wu‘, ‘zhu‘, ‘zhang‘, ‘wang‘]

eg17：

names= ["li","wu","zhu","zhang","wang"]
friends = names[:]…………………………………………………………………………………………复制的是原始母本
names.append("mi")…………………………………………………………………………………………母本修改在副本之后，不影响副本
friends.append("ge")
print("There are competitors:")
print(names)
print("My friends:")
print(friends)

There are competitors:
[‘li‘, ‘wu‘, ‘zhu‘, ‘zhang‘, ‘wang‘, ‘mi‘]
My friends:
[‘li‘, ‘wu‘, ‘zhu‘, ‘zhang‘, ‘wang‘, ‘ge‘]

eg18：

names= ["li","wu","zhu","zhang","wang"]
names.append("mi")
friends = names[:]
print("There are competitors:")
print(names)
print("My friends:")
print(friends)

There are competitors:
[‘li‘, ‘wu‘, ‘zhu‘, ‘zhang‘, ‘wang‘, ‘mi‘]
My friends:
[‘li‘, ‘wu‘, ‘zhu‘, ‘zhang‘, ‘wang‘, ‘mi‘]

eg19：

names= ["li","wu","zhu","zhang","wang"]
friends = names[:]
names.append("mi")
print("There are competitors:")
print(names)
print("My friends:")
print(friends)

There are competitors:
[‘li‘, ‘wu‘, ‘zhu‘, ‘zhang‘, ‘wang‘, ‘mi‘]
My friends:
[‘li‘, ‘wu‘, ‘zhu‘, ‘zhang‘, ‘wang‘]

4.4 元组

4.4.1定义元组
eg20：
dimensions = (200,50)
print(dimensions[0])
print(dimensions[1])

200
50
4.4.2遍历元组
eg21：

dimensions = (200,50)
for dimension in dimensions:
     print(dimension)

200
50
4.4.3（元组不可修改值，但可以给元组赋值）

eg22：
dimensions = (200,50)
dimensions[0]="200"
print(dimensions[0])

Traceback (most recent call last):
  File "C:/Users/25337/PycharmProjects/untitled1/app.py", line 2, in <module>
    dimensions[0]="200"
TypeError: ‘tuple‘ object does not support item assignment

eg23：

dimensions = (200,50)
print("original:")
for dimension in dimensions:
     print(dimension)
dimensions = (250,50)
print("midified:")
for dimension in dimensions:
     print(dimension)

original:
200
50
midified:
250
50

python学习——python编程：从入门到实践（第4章）

原文：https://www.cnblogs.com/ljx12579/p/12571682.html