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Count frequency of values in pandas DataFrame column

Writer Olivia Zamora

I want to count number of times each values is appearing in dataframe.

Here is my dataframe - df:

 status
1 N
2 N
3 C
4 N
5 S
6 N
7 N
8 S
9 N
10 N
11 N
12 S
13 N
14 C
15 N
16 N
17 N
18 N
19 S
20 N

I want to dictionary of counts:

ex. counts = {N: 14, C:2, S:4}

I have tried df['status']['N'] but it gives keyError and also df['status'].value_counts but no use.

5 Answers

You can use value_counts and to_dict:

print df['status'].value_counts()
N 14
S 4
C 2
Name: status, dtype: int64
counts = df['status'].value_counts().to_dict()
print counts
{'S': 4, 'C': 2, 'N': 14}
1

An alternative one liner using underdog Counter:

In [3]: from collections import Counter
In [4]: dict(Counter(df.status))
Out[4]: {'C': 2, 'N': 14, 'S': 4}

You can try this way.

df.stack().value_counts().to_dict()
1

Can you convert df into a list?

If so:

a = ['a', 'a', 'a', 'b', 'b', 'c']
c = dict()
for i in set(a): c[i] = a.count(i)

Using a dict comprehension:

c = {i: a.count(i) for i in set(a)}

See my response in this thread for a Pandas DataFrame output,

count the frequency that a value occurs in a dataframe column

For dictionary output, you can modify as follows:

def column_list_dict(x): column_list_df = [] for col_name in x.columns: y = col_name, len(x[col_name].unique()) column_list_df.append(y) return dict(column_list_df)

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