import pandas as pd

import numpy as np

​

df = pd.DataFrame({'col1':['one', 'two', 'three', 'four']})

​

df['col1'] = df['col1'].map(lambda x: np.nan if x in ['two', 'four'] else x)

df['DataFrame Column'] = df['DataFrame Column'].fillna(0)

​

df.replace(np.nan,0)

​

# Replacing all nan values with 0 in Dataframe

df = df.fillna(0)

#fill nan values with mean

df = df.fillna(df.mean())

#fill nan values with mean

df = df.fillna(df.mean())

>>> df = pd.DataFrame([[1, 2, 3], [4, None, None], [None, None, 9]])

>>> df.fillna(method='ffill')

   0  1  2

0  1  2  3

1  4  2  3

2  4  2  9

​