Asking count frequency in nested list using Python

Question

I have a list like this:

dttrain = [["sunny","hot","high","false","no"],
    ["sunny","hot","high","true","no"],
    ["overcast","hot","high","false","yes"]]

I want to count the frequency by the last index, so for example:

sunnny no = 2 , sunny yes = 0, hot no = 2, hot yes = 1.

I have tried my own code:

c = Counter(x for sublist in dttrain for x in sublist)

But this shows:

Counter({'yes': 9, 'false': 8, 'high': 7, 'normal': 7, 'true': 6, 'mild': 6, 'sunny': 5, 'no': 5, 'rainy': 5, 'hot': 4,'overcast': 4, 'cool': 4})

sunnny no = 2 , sunny yes = 0, hot no = 2, hot yes = 1 -> like this sir, — Fian Eka
– Fian Eka, Commented Nov 4, 2017 at 16:54

halfer · Accepted Answer · 2017-11-05 18:20:34Z

2

Here is some untidy code:

def iterate_key(name, _counter):
    """
    Iterate a key in a dict, create key if it doesn't exist.

    :param str name: Name of key to iterate.
    :param dict[int] _counter: Dictionary storing count data.
    :return: _counter after iterating key.
    """
    if name not in counter:
        _counter[name] = 1
    else:
        _counter[name] += 1
    return _counter


counter = {}
for sub_list in dttrain:
    key_name = '{}_{}'.format(sub_list[0], sub_list[-1])
    counter = iterate_key(key_name, counter)

    key_name = '{}_{}'.format(sub_list[1], sub_list[-1])
    counter = iterate_key(key_name, counter)

print(counter)

edited Nov 5, 2017 at 18:20

halfer

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answered Nov 4, 2017 at 17:00

s3bw

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1 Comment

Fian Eka Over a year ago

Thanks you so much sir, you save my time. Thanks again. Wassalamualaikum.

Transhuman · Accepted Answer · 2017-11-04 17:13:28Z

1

Use the combination of itertools(product and chain) and collections.Counter

from itertools import product, chain
from collections import Counter
{' '.join(k):v for k,v in Counter(chain(*[product(i[:2],[i[-1]]) for i in dttrain])).items()}

Output:

{'hot no': 2, 'hot yes': 1, 'overcast yes': 1, 'sunny no': 2}

edited Nov 4, 2017 at 17:13

answered Nov 4, 2017 at 16:58

Transhuman

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4 Comments

Fian Eka Over a year ago

Oh thank again sir, its simple, but can i get the element from the counter?

Transhuman Over a year ago

@Fian Eka - Please see my Edit

Fian Eka Over a year ago

what a nice code sir, love this. thanks again sir. Wassalamualaikum

s3bw Over a year ago

Ye, my hack is pretty convoluted.

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