平時我們在工作的時候需要統計一篇文章或者網頁出現頻率最高的單詞，或者需要統計單詞出現頻率排序。那么如何完成這個任務了？
例如，我們輸入的語句是 “Hello there this is a test. Hello there this was a test, but now it is not.”，希望得到的升序的結果:
~~~
[[1, 'but'], [1, 'it'], [1, 'not.'], [1, 'now'], [1, 'test,'], [1, 'test.'], [1, 'was'], [2, 'Hello'], [2, 'a'], [2, 'is'], [2, 'there'], [2, 'this']]
~~~
得到降序的結果是:
~~~
[[2, 'this'], [2, 'there'], [2, 'is'], [2, 'a'], [2, 'Hello'], [1, 'was'], [1, 'test.'], [1, 'test,'], [1, 'now'], [1, 'not.'], [1, 'it'], [1, 'but']]
~~~
完成這個結果的代碼如下:
~~~
class Counter(object):
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):
result = [[val, key] for (key, val) in self.dict.items()]
result.sort()
if desc:
result.reverse()
return result
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)
~~~
