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
