import pandas as pd
Get a suitable data set and put it in a DataFrame.
from sklearn.datasets import load_boston
boston = load_boston()
df = pd.DataFrame(boston.data, columns=boston['feature_names'])
Get the unique values in a column.
df['CHAS'].unique()
array([ 0., 1.])
See how many entries with each value.
df['CHAS'].value_counts()
0.0 471
1.0 35
Name: CHAS, dtype: int64
If you spot any errors please let me know on twitter.