《python基础教程（第二版）》学习笔记字典（第4章）

《python基础教程（第二版）》学习笔记字典（第4章）
创建字典：
d={\'key1\':\'value1\',\'key2\':\'value2\'}
lst=[(\'key1\',\'value1\'),(\'key2\',\'value2\')]; d=dict(lst)
d=dict(key1=\'value1\', key2=\'value2\')
字典基本操作：
d={\'key1\':\'value1\',\'key2\':\'value2\'}; len(d) ==> 2 #字典中的键值对数量
d={\'key1\':\'value1\',\'key2\':\'value2\'}; d[\'key1\'] ==> \'value1\' # 键为k的值
d={\'key1\':\'value1\',\'key2\':\'value2\'}; d[\'key1\']=\'NewValue\' ==> \'key1\': \'NewValue\' # 赋值
d={\'key1\':\'value1\',\'key2\':\'value2\'}; del d[\'key2\'] ==> d={\'key1\': \'value1\'} #删除键为k的项
d={\'key1\':\'value1\',\'key2\':\'value2\'}; \'key1\' in d ==> True #检查字典中是否有键k

字典的格式化字符串：
d={\'key1\':\'value1\',\'key2\':\'value2\'}; "%(key1)" % d ?????

字典方法：
d={\'key1\':\'value1\',\'key2\':\'value2\'}; d.clear() ==> d={} # 清除全部项
d={\'key1\':\'value1\',\'key2\':\'value2\'}; d.copy() # 复制
from copy import deepcopy; d={\'key1\':\'value1\',\'key2\':\'value2\'}; deepcopy(d) # 深度复制
{}.fromkeys([\'key1\',\'key2\']) ==> {\'key2\': None, \'key1\': None} #创建字典
d={\'key1\':\'value1\',\'key2\':\'value2\'}; d.get(\'key1\') ==> \'value1\' #获得值
d={\'key1\':\'value1\',\'key2\':\'value2\'}; d.has_key(\'key1\') ==> True #是否有该键
d={\'key1\':\'value1\',\'key2\':\'value2\'}; d.items() ==> [(\'key2\', \'value2\'), (\'key1\', \'value1\')] # 全部项
d={\'key1\':\'value1\',\'key2\':\'value2\'}; d.iteritems() # 迭代全部项
d={\'key1\':\'value1\',\'key2\':\'value2\'}; d.keys() ==> [\'key2\', \'key1\'] #全部键
d={\'key1\':\'value1\',\'key2\':\'value2\'}; d.iterkeys() #迭代全部键
d={\'key1\':\'value1\',\'key2\':\'value2\'}; d.pop(\'key1\') ==>\'value1\', d={\'key2\': \'value2\'} #移除并pop key1
d={\'key1\':\'value1\',\'key2\':\'value2\'}; d.popitem() ==> (\'key2\', \'value2\'), d={\'key1\': \'value1\'} #移除并pop？
d={\'key1\':\'value1\',\'key2\':\'value2\'}; d.setdefault(\'key1\',\'defaultValue1\') ==> \'value1\' #类似于get，如果没有则设置缺省值
d={\'key1\':\'value1\',\'key2\':\'value2\'}; x={\'key2\':\'UPDATE\'}; d.update(x) ==> d={\'key2\': \'UPDATE\', \'key1\': \'value1\'} #用一个字典更新另一个字典
d={\'key1\':\'value1\',\'key2\':\'value2\'}; d.values() ==> [\'value2\', \'value1\'] #全部值
d={\'key1\':\'value1\',\'key2\':\'value2\'}; d.itervalues() # 迭代全部值

len(d) #字典元素个数/长度

遍历字典：

    #!/usr/bin/python
    dict={"a":"apple","b":"banana","o":"orange"}

    print "##########dict######################"
    for i in dict:
            print "dict[%s]=" % i,dict[i]

    print "###########items#####################"
    for (k,v) in dict.items():
            print "dict[%s]=" % k,v

    print "###########iteritems#################"
    for k,v in dict.iteritems():
            print "dict[%s]=" % k,v

    print "###########iterkeys,itervalues#######"
    for k,v in zip(dict.iterkeys(),dict.itervalues()):
            print "dict[%s]=" % k,v