005_004 Python 统计值 并按照次数排序 可以通过字典的值对key进行排序

代码如下：

#encoding=utf-8print '中国'#统计值 并按照次数排序 可以通过字典的值对key进行排序#通过字典来实现class hist(dict):    def add(self,item,increment=1):        self[item]=increment + self.get(item,0)    def counts(self,reverse=False):        aux=[(self[k],k) for k in self]        aux.sort(cmp=None, key=None, reverse=False)        if reverse:            aux.reverse()        return [k for v,k in aux]hist1=hist()hist1.add(3)hist1.add(3)hist1.add(1)print hist1.counts()#通过list来实现class histlist(list):    def __init__(self,n):        list.__init__(self,n*[0])    def add(self,item,increment=1):        self[item] += increment    def counts(self,reverse=False):        aux=[(v,k) for k,v in enumerate(self)]        aux.sort(cmp=None, key=None, reverse=False)        if reverse:aux.reverse()        return [k for v,k in aux]    hist1=histlist(4)hist1.add(3)hist1.add(3)hist1.add(1)print hist1sentence = ''' Hello there this is a test.  Hello there this was a test,           but now it is not. '''words = sentence.split( )c = hist( )for word in words: c.add(word)print "Ascending count:"print c.counts( )print "Descending count:"print c.counts(reverse=True)from operator import itemgetter#itemgetter为获取当前维度的值 （key,val） val为维度一 排序当前维度的值def dict_items_sorted_by_value(d, reverse=False):    return sorted(d.iteritems( ), key=itemgetter(1), reverse=reverse)print dict_items_sorted_by_value(c)

打印结果如下：

中国
[1, 3]
[0, 1, 0, 2]
Ascending count:
['but', 'it', 'not.', 'now', 'test,', 'test.', 'was', 'Hello', 'a', 'is', 'there', 'this']
Descending count:
['this', 'there', 'is', 'a', 'Hello', 'was', 'test.', 'test,', 'now', 'not.', 'it', 'but']
[('not.', 1), ('it', 1), ('but', 1), ('test,', 1), ('now', 1), ('was', 1), ('test.', 1), ('a', 2), ('this', 2), ('is', 2), ('there', 2), ('Hello', 2)]