python 基础之第八天--字典相关

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#####################创建字典######################################

In [11]: dict([('name','bob'),('age',23),['qq',123456]])
Out[11]: {'age': 23, 'name': 'bob', 'qq': 123456}

In [12]: dict((('name','bob'),('age',23),['qq',123456]))        ##dict函数
Out[12]: {'age': 23, 'name': 'bob', 'qq': 123456}

In [13]: aDict = {'name':'bob','age':23,'qq':123456}       ##{}方式

In [14]: aDict
Out[14]: {'age': 23, 'name': 'bob', 'qq': 123456}

  In [20]: {}.fromkeys(['bob','herry','jerry'],7)      ##不同的key,相同的值，‘7’为值value
  Out[20]: {'bob': 7, 'herry': 7, 'jerry': 7}

############关于循环字典取值###############

In [22]: for key in aDict:        ##默认只取key
   ....:     print key
   ....:     
qq
age
name

In [23]: for key in aDict:       ##key与value一起取
    print '%s-->%s' % (key,aDict[key])
   ....:     
qq-->123456
age-->23
name-->bob

#########特殊格式输出################
In [36]: aDict
Out[36]: {'age': 23, 'name': 'bob', 'qq': 123456}

In [37]: '%(name)s --> %(age)s' % aDict
Out[37]: 'bob --> 23'

##############删除（不常用），弹出与清空#############

#######aDict.pop##########
In [39]: aDict
Out[39]: {'age': 23, 'name': 'bob', 'qq': 123456}

In [41]: aDict.pop('age')  ###因为字典是无序的，所以需要指名pop哪个key
Out[41]: 23

In [42]: aDict
Out[42]: {'name': 'bob', 'qq': 123456}

  In [43]: aDict.popitem()       ###popitem（）是随机弹的，几乎用不到，括号内不接受参数
  Out[43]: ('qq', 123456)

  In [46]: uu = aDict.copy()    #复制字典

  In [47]: uu
  Out[47]: {'name': 'bob'}

  In [48]: uu.clear()          ###清空字典

  In [49]: uu
  Out[49]: {}

##########字典的in 与not in #############

In [63]: aDict
Out[63]: {'age': 23, 'name': 'herry'}

In [64]: 'age' in aDict          ###通过key查看是否在字典中，而不是value
Out[64]: True

#############字典长度##############

In [63]: aDict
Out[63]: {'age': 23, 'name': 'herry'}

In [66]: len(aDict)
Out[66]: 2

###########判断是否可以作为字典的key##########

In [67]: hash('naem')
Out[67]: -4166578487153698939

In [68]: hash(20)    
Out[68]: 20

In [69]: hash((10,30))
Out[69]: 3713074054223687331

In [70]: hash([10,30])
---------------------------------------------------------------------------
TypeError                                 Traceback (most recent call last)
<ipython-input-70-2766bfecf01d> in <module>()
----> 1 hash([10,30])

TypeError: unhashable type: 'list'

总结：通过hash函数，如果不报错，就是可以作为字典的key，我们会发现key都是不可变对象

#############字典的拷贝################

In [71]: aDict
Out[71]: {'age': 23, 'name': 'herry'}

In [72]: bDict = aDict.copy()

In [73]: bDict
Out[73]: {'age': 23, 'name': 'herry'}

In [74]: aDict
Out[74]: {'age': 23, 'name': 'herry'}

In [75]: id(aDict)
Out[75]: 45174528

In [76]: id(bDict)
Out[76]: 45199760

###########字典的get 用法（常用）############

In [71]: aDict
Out[71]: {'age': 23, 'name': 'herry'}

In [77]: aDict.get('age')    ###get key为‘age’ 的值23
Out[77]: 23

In [78]: aDict.get('qq')      ###get 不存在的key,返回值None

In [79]: print aDict.get('qq')
None

In [80]: aDict.get('qq','not found')      ########自定义，如果get 的key存在，则返回对应的值，不存在则返回我们定义的值，这边是‘not found’
Out[80]: 'not found'

In [81]: aDict.get('age','not found')  
Out[81]: 23

In [82]: aDict.get('name','not found')   
Out[82]: 'herry'

备注：

  In [83]: help(aDict.get)
  Help on built-in function get:

get(...)

      D.get(k[,d]) -> D[k] if k in D, else d. d defaults to None.

In [90]: aDict.setdefault('age',33)      ####setdefault key，存在，则返回相对应的值，不存在则增加key-value
Out[90]: 20

In [91]: aDict
Out[91]: {'age': 20, 'name': 'herry'}

In [92]: aDict.setdefault('qq',333333)
Out[92]: 333333

In [93]: aDict
Out[93]: {'age': 20, 'name': 'herry', 'qq': 333333}

In [94]: help(aDict.setdefault)
Help on built-in function setdefault:

setdefault(...)
    D.setdefault(k[,d]) -> D.get(k,d), also set D[k]=d if k not in D

##########################################################

In [100]: aDict
Out[100]: {'age': 20, 'name': 'herry', 'qq': 333333}

In [96]: aDict.keys()
Out[96]: ['qq', 'age', 'name']

In [97]: aDict.values()     
Out[97]: [333333, 20, 'herry']

In [98]: aDict.items()
Out[98]: [('qq', 333333), ('age', 20), ('name', 'herry')]

实战案例：

################################################################

[root@master script]# cat info.py 
#!/usr/bin/python
# coding:utf-8


user_dic = {'fush':123}


def register():
    username = raw_input('请输入你的注册用户名: ')
    password = raw_input('请输入你的注册密码:')
    user_dic.setdefault(username,password)
    print user_dic    
def login():
    username = raw_input('请输入你的用户名: ')
    while True:
        password = raw_input('请输入你的密码:')
        pwd = user_dic.get(username)
        if str(pwd) == password:
            print '登录系统成功！'
            break
        else:
            print '你输入的密码不正确,请重新输入'

def show_menu():
    CMDs = {'1':register,'2':login}
    username = raw_input('请输入你的用户名: ')
    str_value = user_dic.get(username,'not found')
    if str_value == 'not found':
        print '%s用户名不存在,请输入数字1注册' % username
    else:
        print '%s用户名已存在,可直接输入数字2登录系统' % username
    while True:
        prompt = """(1)注册用户
(2)登录系统
(3)退出
请输入的你的选择(1/2/3):"""
        choice = raw_input(prompt)
        if choice == '3':
            break
        CMDs[choice]()
if __name__ == '__main__':
    show_menu()

 ###############生成器表达式（与列表解析类似）###############

In [19]: [i ** 2 for i in range(1,11)]
Out[19]: [1, 4, 9, 16, 25, 36, 49, 64, 81, 100]

In [20]: [i ** 2 for i in range(1,11) if i%2]
Out[20]: [1, 9, 25, 49, 81]

In [21]: [i ** 2 for i in range(1,11) if i % 2]
Out[21]: [1, 9, 25, 49, 81]

In [22]: [i ** 2 for i in range(1,11) if not i % 2]
Out[22]: [4, 16, 36, 64, 100]

In [23]: (i ** 2 for i in range(1,11) if not i % 2) 
Out[23]: <generator object <genexpr> at 0x16459b0>

In [24]: a = (i ** 2 for i in range(1,11) if not i % 2)

案例：打印出一副扑克牌

puke = ['%s_%s' % (color,i) for color in ('Red','Cube','Black','Flower') for i in (range(2,11) + ['A','J','K','Q'])]

结果：
['Red_2',
 'Red_3',
 'Red_4',
 'Red_5',
 'Red_6',
 'Red_7',
 'Red_8',
 'Red_9',
 'Red_10',
 'Red_A',
 'Red_J',
 'Red_K',
 'Red_Q',
 'Cube_2',
 'Cube_3',
 'Cube_4',
 'Cube_5',
 'Cube_6',
 'Cube_7',
 'Cube_8',
 'Cube_9',
 'Cube_10',
 'Cube_A',
 'Cube_J',
 'Cube_K',
 'Cube_Q',
 'Black_2',
 'Black_3',
 'Black_4',
 'Black_5',
 'Black_6',
 'Black_7',
 'Black_8',
 'Black_9',
 'Black_10',
 'Black_A',
 'Black_J',
 'Black_K',
 'Black_Q',
 'Flower_2',
 'Flower_3',
 'Flower_4',
 'Flower_5',
 'Flower_6',
 'Flower_7',
 'Flower_8',
 'Flower_9',
 'Flower_10',
 'Flower_A',
 'Flower_J',
 'Flower_K',
 'Flower_Q']


  In [52]: import random 
  In [50]: random.shuffle(puke)    #########将扑克牌随机打乱（洗牌）
三个人打牌：

In [52]: random.shuffle(puke)

In [53]: a = puke[::3]

In [54]: a
Out[54]:
['Red_3',
'Cube_9',
'Black_Q',
'Black_5',
'Cube_J',
'Flower_6',
'Flower_K',
'Red_Q',
'Red_5',
'Cube_2',
'Cube_4',
'Flower_8',
'Flower_9',
'Red_A',
'Red_6',
'Cube_6',
'Flower_5',
'Black_7']

In [55]: b = puke[1::3]

In [56]: b
Out[56]:
['Cube_3',
'Cube_A',
'Cube_5',
'Black_A',
'Black_9',
'Flower_10',
'Red_10',
'Cube_K',
'Flower_2',
'Black_J',
'Flower_7',
'Cube_7',
'Black_2',
'Black_8',
'Cube_8',
'Black_3',
'Black_K']

In [57]: c = puke[2::3]

In [58]: c
Out[58]:
['Black_10',
'Red_9',
'Black_6',
'Cube_Q',
'Flower_J',
'Red_2',
'Red_K',
'Red_8',
'Flower_A',
'Red_4',
'Red_J',
'Flower_3',
'Flower_Q',
'Red_7',
'Cube_10',
'Black_4',
'Flower_4']

###########文件的输入输出#########################

 #################标准文件的输入与输出################

#############os模块#####################

In [19]: import os 

In [20]: import shutil

In [21]: os.chdir('/home')     ###相当于shell 的cd 命令

In [25]: os.mkdir('demo')     ###相当于shell 的mkdir 命令

In [23]: os.getcwd()     ###相当于shell 的pwd 命令
Out[23]: '/home'

In [29]: os.listdir('.')     ###相当于shell 的ls 命令
Out[29]: ['herry', 'honey', 'tiantian', 'fush', 'jerry', 'master']

In [30]: os.mknod('fush.txt')     ###创建一个新文件，相当于shell 的touch

  In [41]: os.chmod('/home/11111.txt',0777)     ##修改文件权限，前面需要加0，加0是八进制数，十六进制是0x,二进制是0b

  In [42]: os.symlink('/etc/passwd','mima')    ##创建软链接，将‘/etc/passwd’ 链接到‘mima’

  [root@master home]# ll

  lrwxrwxrwx  1 root  root    11 Aug 14 15:40 mima -> /etc/passwd

  In [50]: os.rmdir('/home/tiantian/')   ##不能删除非空目录，使用shutil.rmtree('/home/tiantian/')

  In [52]: shutil.copy('/etc/hosts','/home/')   ###复制文件

##########os.path.操作###############

In [55]: os.path.dirname('/home/master/script/ip.py')    ##查看上一层目录
Out[55]: '/home/master/script'

In [63]: os.path.split('/home/master/script/ip.py')    ##切割
Out[63]: ('/home/master/script', 'ip.py')

In [64]: os.path.basename('/home/master/script/ip.py')        ##取得文件名
Out[64]: 'ip.py'

In [65]: os.path.join('/home/master/script/','ip.py')      ##拼接目录与文件
Out[65]: '/home/master/script/ip.py'

In [66]: os.path.splitext('/home/master/script/ip.py')      ###获取点后面扩展名
Out[66]: ('/home/master/script/ip', '.py')

In [72]: os.path.abspath('info.py')               ##得到文件的绝对路劲
Out[72]: '/home/master/script/info.py'

#############cPickle模块###################

语句例子：

In [83]: import cPickle as p        #写入

In [84]: f = open('demo.txt','w')

In [85]: p.dump({'name':'bob','age':22},f)

In [86]: f.close()

In [87]: f = open('demo.txt')    #打开读取

In [88]: aDict = p.load(f)

In [89]: aDict
Out[89]: {'age': 22, 'name': 'bob'}

#################匿名函数##################

lambda:

In [96]: a = lambda x,y :x+y    ###格式： lambda 参数：表达式

In [97]: a(10,20)
Out[97]: 30