maintain a counter of items using dic

counter_dictionary.py

from collections import defaultdict

# method 1
my_dict = defaultdict(int)
my_dict[key] += 1

# method 2
my_dict = {}
my_dict[key] = my_dict.get(key, 0) + 1

# method 3
from collections import Counter
Counter(['apple','red','apple','red','red','pear'])


# Be careful if you want to store list as default value
# https://stackoverflow.com/questions/5772148/python-using-dictionary-get-method-to-return-empty-list-by-default-returns-none
# Use something like:
dict = defaultdict(list)
dict[i].append( j )

# To get sorted
# https://stackoverflow.com/questions/20950650/how-to-sort-counter-by-value-python

from collections import Counter
x = Counter({'a':5, 'b':3, 'c':7})
x.most_common()

from collections import Counter, OrderedDict
x = Counter({'a':5, 'b':3, 'c':7})
y = OrderedDict(x.most_common())

# Pandas df
import pandas as pd

pd.DataFrame.from_dict(data)

# or

>>> data = {'row_1': [3, 2, 1, 0], 'row_2': ['a', 'b', 'c', 'd']}
pd.DataFrame.from_dict(data, orient='index')