marks = marks.drop([marks.isnull().sum()==5]) code example

Example 1: df count missing values

In [5]: df = pd.DataFrame({'a':[1,2,np.nan], 'b':[np.nan,1,np.nan]})

In [6]: df.isna().sum()
Out[6]:
a    1
b    2
dtype: int64

Example 2: python count null values in dataframe

# Count total missing values in a dataframe

df.isnull().sum().sum()

# Gives a integer value