Formatting output of Counter

Question

I have used Counter to count the number of occurrence of the list items. I have trouble in displaying it nicely. For the below code,

category = Counter(category_list)
print category

the following is the output,

Counter({'a': 8508, 'c': 345, 'w': 60})

I have to display the above result as follows,

a 8508
c 345
w 60

I tried to iterate over the counter object but I'm unsuccessful. Is there a way to print the output of the Counter operation nicely?

Do you want the output sorted alphabetically by the key or in descending order based on the value? — DSM, Dec 01 '13 at 19:55
Sorry, I should have mentioned that in my question but the answers have already covered both sorted and unsorted ways. I wanted to display the result in descending order based upon the values. — , Dec 01 '13 at 21:06

score 30 · Accepted Answer · edited May 23 '17 at 11:46

Counter is essentially a dictionary, thus it has keys and corresponding values - just like the ordinary dictionary. From the documentation:

A Counter is a dict subclass for counting hashable objects. It is an unordered collection where elements are stored as dictionary keys and their counts are stored as dictionary values.

You can use this code:

>>> category = Counter({'a': 8508, 'c': 345, 'w': 60})
>>> category.keys() 
dict_keys(['a', 'c', 'w'])
>>> for key, value in category.items():
...     print(key, value)
... 
a 8508
c 345
w 60

However, you shouldn't rely on the order of keys in dictionaries.

Counter.most_common is very useful. Citing the documentation I linked:

Return a list of the n most common elements and their counts from the most common to the least. If n is not specified, most_common() returns all elements in the counter. Elements with equal counts are ordered arbitrarily.

(emphasis added)

>>> category.most_common() 
[('a', 8508), ('c', 345), ('w', 60)]
>>> for value, count in category.most_common():
...     print(value, count)
...
a 8508
c 345
w 60

Ashwini Chaudhary · Answer 2 · 2013-12-01T19:46:36.547

10

print calls __str__ method of Counter class, so you need to override that in order to get that output for print operation.

from collections import Counter
class MyCounter(Counter):
    def __str__(self):
        return "\n".join('{} {}'.format(k, v) for k, v in self.items())

Demo:

>>> c = MyCounter({'a': 8508, 'c': 345, 'w': 60})
>>> print c
a 8508
c 345
w 60

edited Dec 01 '13 at 19:46

answered Dec 01 '13 at 19:38

Ashwini Chaudhary

244,495
58
464
504

wirthra · Answer 3 · 2020-04-02T17:38:45.340

4

If you do not care abut having brackets at the beginning and the end another option is using pprint. It sorts the counter alphabetically for you.

import pprint
from collections import Counter

category = Counter({'a': 8508, 'c': 345, 'w': 60})
pprint.pprint(dict(category),width=1)

Output:

{'a': 8508,
 'c': 345,
 'w': 60}

edited Apr 02 '20 at 17:38

answered Apr 02 '20 at 17:26

wirthra

153
1
10

score 3 · Answer 4 · 2013-12-01T19:46:50.127

3

This works:

>>> from collections import Counter
>>> counter = Counter({'a': 8508, 'c': 345, 'w': 60})
>>> for key,value in sorted(counter.iteritems()):
...     print key, value
...
a 8508
c 345
w 60
>>>

Here is a reference on sorted and one on dict.iteritems.

edited Dec 01 '13 at 19:46

answered Dec 01 '13 at 19:37

Instead of `sorted(counter.iteritems())` you should use `counter.most_common()` – Yaakov Bressler Dec 22 '22 at 17:41

score 1 · Answer 5 · answered Oct 11 '21 at 15:19

I was just looking for a nice in-line formatter:

from collections import Counter

c = Counter({'a': 8508, 'c': 345, 'w': 60})
cs = sorted(c.items(), key=lambda n: n[1], reverse=True)
print(", ".join(f"{el[1]}× {el[0]}" for el in cs))

gives

8508× a, 345× c, 60× w

Formatting output of Counter

5 Answers5

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