## {{{ http://code.activestate.com/recipes/52231/ (r1)
class Counter:
    def __init__(self):
        self.dict = {}
    def add(self,item):
        count = self.dict.setdefault(item,0)
        self.dict[item] = count + 1
    def counts(self,desc=None):
        '''Returns list of keys, sorted by values.
        Feed a 1 if you want a descending sort.'''
        i = map(lambda t: list(t),self.dict.items())
        map(lambda r: r.reverse(),i)
        i.sort()
        if desc:
            i.reverse()
        return i

if __name__ == '__main__':

    '''Produces:

>>> Ascending count:
[[1, 'but'], [1, 'it'], [1, 'not.'], [1, 'now'], [1, 'test,'], [1, 'test.'], [1, 'was'], [2, 'Hello'], [2, 'a'], [2, 'is'], [2, 'there'], [2, 'this']]
Descending count:
[[2, 'this'], [2, 'there'], [2, 'is'], [2, 'a'], [2, 'Hello'], [1, 'was'], [1, 'test.'], [1, 'test,'], [1, 'now'], [1, 'not.'], [1, 'it'], [1, 'but']]
    '''

    sentence = "Hello there this is a test.  Hello there this was a test, but now it is not."
    words = sentence.split()
    c=Counter()
    for word in words:
        c.add(word)
    print "Ascending count:"
    print c.counts()
    print "Descending count:"
    print c.counts(1)
## end of http://code.activestate.com/recipes/52231/ }}}

http://code.activestate.com/recipes/52231-count-items-and-sort-by-incidence/

Count items and sort by incidence

list, python

Python