python第二章（2）列表

names=["zhangyang","guyun","xiangpeng","leiming","xuliangchen"]

#查看
print(names[0],names[2])
print(names[0:2])  #切片：前两个
print(names[-1])   #从后面开始取
print(names[-3:-1])  #取出guyun,xiangpeng
print(names[-3:])  #后3个

#追加到最后
names.append("leihaidong")
#print(names)
#插入
names.insert(1,"leiming")
names.insert(3,"xinzhiyu")   
print(names)
#改
names[2]="xiedi"    #correct
print(names)
#删
#names.remove("leiming")  #delete1
#names.pop(1)    #delete2
print(names)

#显示某一项的位置
print(names.index('xiangpeng'))
#显示某一项出现的次数
print(names.count('leiming'))

#names.clear()  #清空

#names.reverse()  #反转
#names.sort()  #排序，按照ascii码表排序

#扩展，后删除列表
names2=[1,2,3]
names.extend(names2)
del names2
print(names)


#浅copy

names=["zhangyang","guyun","xiangpeng",["alex","jack"],"leiming","xuliangchen"]

names3=names.copy() #第1种
'''
names3=copy.copy(names)   #第2种，前面要加import copy
names3=names[:]   #第3种，全切片
'''
print(names)
print(names3)

names2=names

names[2]="向鹏"
names[3][0]="Alex Angle"
names3[3][1]="JACK"
print(names)
print(names3)

print(names2)

#结果

['zhangyang', 'guyun', 'xiangpeng', ['alex', 'jack'], 'leiming', 'xuliangchen']
['zhangyang', 'guyun', 'xiangpeng', ['alex', 'jack'], 'leiming', 'xuliangchen']

['zhangyang', 'guyun', '向鹏', ['Alex Angle', 'JACK'], 'leiming', 'xuliangchen']
['zhangyang', 'guyun', 'xiangpeng', ['Alex Angle', 'JACK'], 'leiming', 'xuliangchen']

在复制时，第一层相当于重新copy了一份；而第二层相当于指针(无论改names还是names3的第二层，两个列表都发生改变）

['zhangyang', 'guyun', '向鹏', ['Alex Angle', 'JACK'], 'leiming', 'xuliangchen']

#深copy(一般不用）

import copy

names4=copy.deepcopy(names)

 

names[2]="向鹏"
names[3][0]="Alex Angle"
print(names4)

 

 

#结果
['zhangyang', 'guyun', 'xiangpeng', ['alex', 'jack'], 'leiming', 'xuliangchen']

#跳着打印

names=["zhangyang","guyun","xiangpeng","leiming","xuliangchen"]

print(names[0:-1:2])
print(names[::2])

#结果

['zhangyang', 'xiangpeng']
['zhangyang', 'xiangpeng', 'xuliangchen']

 

#浅copy示例（夫妻共有的银行账户）

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

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

p1[0]='alex'
p2[0]='alice'

p1[1][1]-=70
print(p1)
print(p2)

#结果

['alex', ['saving', 30]]
['alice', ['saving', 30]]