Python 学习笔记【09】列表、元组

　　定义列表

names = ["Zhangyang", "Guyun", "Xiangpeng", "Xuliangchen"]

　　通过下标取列表中的值

print(names[0], names[2])

　　切片:取多个元素  

print(names[1:3])  # 取第二个到第三个值  注：顾头不顾尾

print(names[0:3]) # 取第一个到第三个值

print(names[-1])  # 取最后一个值

print(names[-2])  # 取倒数第二个值

print(names[-3:-1])  # 取倒数第三个到倒数第二个值  注：从左往右取值

print(names[-2:])  # 取倒数第二个到倒数最后一个值  注：省略冒号后的值，取到最后一个

print(names[:3])  # 取第一个到第三个值  注：省略冒号前的值，从第一个开始取值

print(names[:])

 　　追加元素

names.append("Leihaidong")

 　　插入元素

names.insert(1, "Chenzhonghua")
names.insert(3, "Xinzhiyu")

　　修改元素

names[2] = "Xiedi"

 　　删除元素

names.remove("Chenzhonghua")  # 方法一

del names[1]  # 方法二

names.pop()  # 无下标，默认删除最后一个

names.pop(1)  # 方法三

 　　查找元素

print(names.index("Xiedi"))

print(names[names.index("Xiedi")])

　　统计元素

print(names.count("Chenzhonghua"))

　　清空列表

names.clear()

　　反转列表

names.reverse()

 　　排序列表

names.sort()

 　　扩展列表

names = ["Zhangyang", "Guyun", "Xiangpeng", "Chenzhonghua", "Xuliangchen"]

names2 = [1, 2, 3, 4]

names.extend(names2)

print(names, names2)

　　删除列表

del names2

 　拷贝列表

names = ["Zhangyang", "Guyun", "Xiangpeng", "Chenzhonghua", "Xuliangchen"]

names2 = names.copy()

print(names)

print(names2)

　　拷贝列表为浅复制，只复制一层，深层指向内存地址

names = ["Zhangyang", "Guyun", "Xiangpeng", ["alex", "jack"], "Chenzhonghua", "Xuliangchen"]

names2 = names.copy()

names[2] = "向鹏"

names[3][0] = "ALEXANDER"

print(names)

print(names2)

 　　如果列表赋值给列表，则只会指向内存地址，与字符串及数字赋值不同

names = ["Zhangyang", "Guyun", "Xiangpeng", ["alex", "jack"], "Chenzhonghua", "Xuliangchen"]

names2 = names

names[2] = "向鹏"

names[3][0] = "ALEXANDER"

print(names)

print(names2)

　　深层复制，导入copy模块

import copy

names = ["Zhangyang", "Guyun", "Xiangpeng", ["alex", "jack"], "Chenzhonghua", "Xuliangchen"]

names2 = copy.deepcopy(names)  # 深Copy，ames2 = copy.copy(names)  为浅Copy

names[2] = "向鹏"

names[3][0] = "ALEXANDER"

print(names)

print(names2)

　　列表内元素的循环

names = ["Zhangyang", "Guyun", "Xiangpeng", ["alex", "jack"], "Chenzhonghua", "Xuliangchen"]

for i in names:
    print(i) 

　　跳跃切片

names = ["Zhangyang", "Guyun", "Xiangpeng", ["alex", "jack"], "Chenzhonghua", "Xuliangchen"]

print(names[0:-1:1])  # 从第一个值开始，到倒数第二个，每跳跃一个值切片

　　省略写法

names = ["Zhangyang", "Guyun", "Xiangpeng", ["alex", "jack"], "Chenzhonghua", "Xuliangchen"]

print(names[::2])  # 从第一个值开始，到最后一个，每跳跃一个值切片

names = ["Zhangyang", "Guyun", "Xiangpeng", ["alex", "jack"], "Chenzhonghua", "Xuliangchen"]

print(names[:])  # 从第一个值开始，到最后一个

 　　浅Copy的三种方式

import copy

person = ['name', ['a', 100]]

p1 = copy.copy(person)
p2 = person[:]
p3 = list(person)

　　浅Copy的应用实例

import copy

person = ['name', ['saving', 100]]

p1 = person[:]
p2 = person[:]

p1[0] = 'husband'
p2[0] = 'wife'

p1[1][1]=50

print(p1)
print(p2)

 　　元组

　　元组是存一组数，只是它一旦创建，便不能再修改，所以又叫只读列表

　　它有2个方法，一个是count，一个是index

names = ('jack', 'Alex')