Count frequency of a column in pasdas DataFrame.

freq.py

import pandas as pd
from sklearn import datasets
iris = datasets.load_iris()

iris_df = pd.DataFrame(iris.data, columns=iris.feature_names)
iris_df['species'] = iris.target
mapping = {0 : 'setosa', 1: 'versicolor', 2: 'virginica'}
iris_df = iris_df.replace({'species': mapping})

def freq(data, var):
    freq = data[var].value_counts().reset_index()
    freq.columns = [var, 'count']
    freq['percent'] = freq['count'] / freq['count'].sum() * 100
    freq['percent'] = freq['percent'].map('{:,.2f}%'.format)
    return(freq)

freq(iris_df, "species")
#       species  count percent
# 0      setosa     50  33.33%
# 1   virginica     50  33.33%
# 2  versicolor     50  33.33%