python dict更新差异 [英] python dict update diff
本文介绍了python dict更新差异的处理方法,对大家解决问题具有一定的参考价值,需要的朋友们下面随着小编来一起学习吧!
问题描述
>>> a = {'a':'hamburger','b':'fries','c':'coke'}
>>> b = {'b':'fries','c':'pepsi','d':'ice cream'}
>>> a.diff(b)
{'c':'pepsi','d':'ice cream'}
>>> a.update(b)
>>>> a
{'a':'hamburger','b':'fries','c':'pepsi','d':'ice cream'}
我正在寻找一个改变值的字典,如a.diff(b)的结果所示
解决方案
不,您可以将dict子类提供变更通知。
class ObservableDict(dict):
def __init __(self,* args,** kw):
self.observers = []
super(ObservableDict,self).__ init __(* args,** kw)
def observe(self,observer):
self.observers.append(observer )
def __setitem __(self,key,value):
在self.observers中为o
o.notify(self,key,self [key],value)
super (ObservableDict,self).__ setitem __(key,value)
def update(self,anotherDict):
for另一个代码:
self [k] = anotherDict [k]
class Watcher(object):
def notify(self,observable,key,old,new):
printChange to,observable,at,key
w = Watcher()
a = ObservableDict({'a':'hamburger','b':'fries','c':'coke'})
a.observe(w)
b = {'b':'fries','c':'pepsi'}
a.update(b)
请注意,这里定义的超类Watcher不会检查是否存在真实更改;它只是注意到有一个变化。
Does python have any sort of built in functionality of notifying what dictionary elements changed upon dict update? For example I am looking for some functionality like this:
>>> a = {'a':'hamburger', 'b':'fries', 'c':'coke'}
>>> b = {'b':'fries', 'c':'pepsi', 'd':'ice cream'}
>>> a.diff(b)
{'c':'pepsi', 'd':'ice cream'}
>>> a.update(b)
>>> a
{'a':'hamburger', 'b':'fries', 'c':'pepsi', 'd':'ice cream'}
I am looking to get a dictionary of the changed values as shown in the result of a.diff(b)
解决方案
No, but you can subclass dict to provide notification on change.
class ObservableDict( dict ):
def __init__( self, *args, **kw ):
self.observers= []
super( ObservableDict, self ).__init__( *args, **kw )
def observe( self, observer ):
self.observers.append( observer )
def __setitem__( self, key, value ):
for o in self.observers:
o.notify( self, key, self[key], value )
super( ObservableDict, self ).__setitem__( key, value )
def update( self, anotherDict ):
for k in anotherDict:
self[k]= anotherDict[k]
class Watcher( object ):
def notify( self, observable, key, old, new ):
print "Change to ", observable, "at", key
w= Watcher()
a= ObservableDict( {'a':'hamburger', 'b':'fries', 'c':'coke'} )
a.observe( w )
b = {'b':'fries', 'c':'pepsi'}
a.update( b )
Note that the superclass Watcher defined here doesn't check to see if there was a "real" change or not; it simply notes that there was a change.
这篇关于python dict更新差异的文章就介绍到这了,希望我们推荐的答案对大家有所帮助,也希望大家多多支持IT屋!
查看全文