value counts problem in a column contained a list (python)

Question

value_counts can’t count values in list.

Hi,
Some of the columns in my dataframe have a list.

X	Y
101	`['A']`
200	`['A','O']`
32	`['B']`
41	`['A','AB,'O']`
202	`['A']`

When i use value_counts() ; i get this result:


`['A']`	2
`['A' , 'O']`	1
`['B']`	1
`['A','AB','O']`	1

But i want this results:


`['A']`	4
`['O']`	2
`['B']`	1
`['AB']`	1

Is there any code for it?

Asked By: azade0

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Source

Answer 1

I think explode will work for you

import pandas as pd
df = pd.DataFrame({"a": [['A'], ['A', 'O'], ['B'], ['A', 'AB', 'O'], ['A']]})
df["a"].explode().value_counts()

# output
A     4
O     2
B     1
AB    1

# If your dataframe is like this
from ast import literal_eval
df = pd.DataFrame({"a": ["['A']", "['A', 'O']", "['B']", "['A', 'AB', 'O']", "['A']"]})
df["a"].apply(literal_eval).explode().value_counts()

Answered By: assume_irrational_is_rational

Answer 2

You could collect the lists, unpack the items (using itertools.chain) and then count (using collections.Counter) and put it back into a pandas object

from itertools import chain
from collections import Counter
df['Y'] = df['Y'].apply(lambda x: eval(x)) #converts to list
pd.Series(Counter(chain.from_iterable(df['Y'].values)))

Output

Answered By: Mortz

value counts problem in a column contained a list (python)

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