Unique values in a column

In [1]:

import pandas as pd

Get a suitable data set and put it in a DataFrame.

In [2]:

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.

In [19]:

df['CHAS'].unique()

Out[19]:

array([ 0.,  1.])

See how many entries with each value.

In [20]:

df['CHAS'].value_counts()

Out[20]:

0.0    471
1.0     35
Name: CHAS, dtype: int64