import pandas as pd
import numpy as np

dates = pd.date_range('20130101', periods=6)
df = pd.DataFrame(np.arange(24).reshape((6,4)), index=dates, columns=['A', 'B', 'C', 'D'])

df.iloc[0, 1] = np.nan
df.iloc[1, 2] = np.nan
print(df)

print(df.dropna(axis = 0, how='any')) # how = {'any', 'all'}
print(df.dropna(axis = 1, how='any')) # how = {'any', 'all'}
print(df.dropna(axis = 1, how='all')) # how = {'any', 'all'}

print(df.fillna(value=0))
print(df.isnull())
print(np.any(df.isnull())==True)