Python学习心得(二) 字典Dictionary

前言 . 在Python中字典就是一系列的键值对，一种可变容器，可以存储任意对象，也被称作关联数组或哈希表。

1.基本语法

用一对花括号{}中的一系列键值对表示，键与值之间用冒号分隔，键值对之间用逗号分隔，例如：

blogger = {'name': 'binguo','age': 27}

2.访问字典中的值

print 'name:'+ blogger['name'] +' age:' +str(blogger['age'])

3.添加键值对

blogger['gender'] = 'male'print blogger #{'gender': 'male', 'age': 27, 'name': 'binguo'}

4.修改字典中的值

blogger['name'] = 'binguo168'print blogger['name'] #binguo168

5.删除键值对

del blogger['age']print blogger #{'gender': 'male', 'name': 'binguo168'}

6.遍历所有的键值对

for key,value in blogger.items():    print '\nkey:'+key    print 'value:'+value'''key:gendervalue:malekey:namevalue:binguo168''' 

7.遍历字典中所有的键

for key in blogger.keys():    print 'key:'+key"""key:genderkey:name"""    #按顺序遍历字典中所有的键for key in sorted(blogger.keys()): #对blogger.keys()方法调用了 临时性排序函数sorted()    print 'key:'+key

8.遍历字典中所有的值

for value in blogger.values():    print 'value:'+value    """value:malevalue:binguo168"""#当字典中含有重复元素时，可以集合(set)予以处理，比如：blogger['NameUsedBefore'] = 'binguo168'#此时blogger字典的value值中就出现了重复元素:['male', 'binguo168', 'binguo168']print blogger.values() #通过转换集合的方式，剔除了重复元素for newvalue in set(blogger.values()):    print newvalue """binguo168male"""

9.嵌套(列表中嵌套字典、字典中嵌套列表、字典中嵌套字典)

#列表嵌套字典blogger2 = [{'name':'bingru','age':26},{'company':'csdn','salary':'you guess'}]for message in blogger2:    print message#字典嵌套列表blogger3 ={'personmessage':['binguo','male','27'],'hobby':'study'}for key3,value3 in blogger3.items():    print '\nkey3:' + key3    print value3 #字典嵌套字典bloggers = {'binguo':{'gender':'male','age':27},            'binguo168':{'hobby':'study','education':'graduate from primary school'}            }      for blogger,blogger_info in bloggers.items():    print '\nblogger' + blogger    print blogger_info"""bloggerbinguo168{'hobby': 'study', 'education': 'graduate from primary school'}bloggerbinguo{'gender': 'male', 'age': 27}""" 

参考资料 《Python编程从入门到实践》