I've often found it necessary to produce ascending or descending counts -- the most or least common words in a file, popular pages on a website, etc. This is a simple class that makes this easy.
Python, 35 lines
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Copy to clipboard1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 | 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)
|
The counts() method is where all the action is. It takes the object's dictionary and produces an ascending or descending sort of keys by values, returning a list.
List comprehension instead of map(). If you use a Python 2 list comprehension instead of the two map() calls, the code is a little easier to read:
PS. It would be cool to have a link to download each Cookbook code snippet instead of having to copy, paste and then fix the whitespace. Fred Bremmer
Text Source available. Now you can by clicking on "Text Source"