Python How To Use Counter On Objects According To Attributes

I have a class named record, which stores information of log record; class Record(): def __init__(self, **kwargs): for key, value in kwargs.items(): setatt

Solution 1:

You should be able to just iterate over all the records and pass url values to Counter, like so:

records = [r1, r2, r3, ...]
url_counter = Counter(r.url for r in records)
print(url_counter['www.google.com'])

Solution 2:

There was a subtle bug in my previous answer, and while fixing it I came up with a much simpler and faster way to do things which no longer uses itertools.groupby().

The updated code below now features a function designed to do exactly what you want.

from collections import Counter
from operator import attrgetter

class Record(object):
    def __init__(self, **kwargs):
        for key, value in kwargs.iteritems():
             setattr(self, key, value)

records = [Record(uid='001', url='www.google.com', status=200),
           Record(uid='002', url='www.google.com', status=404),
           Record(uid='339', url='www.ciq.com',    status=200)]

def count_attr(attr, records):
    """ Returns Counter keyed by unique values of attr in records sequence. """
    get_attr_from = attrgetter(attr)
    return Counter(get_attr_from(r) for r in records)

for attr in ('status', 'url'):
    print('{!r:>8}: {}'.format(attr, count_attr(attr, records)))

Output:

'status': Counter({200: 2, 404: 1})
   'url': Counter({'www.google.com': 2, 'www.ciq.com': 1})