pandas why isnull() count() code example

Example 1: python count null values in dataframe

# Count total missing values in a dataframe

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

# Gives a integer value

Example 2: find the number of nan per column pandas

In [1]: s = pd.Series([1,2,3, np.nan, np.nan])

In [4]: s.isna().sum()   # or s.isnull().sum() for older pandas versions
Out[4]: 2