count if null column pandas 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: python if column is null then

df['real_lastName'] = np.where(df['LastName'].isnull(), df['Middle'], df['LastName'] )

print (df)
  FirstName Middle LastName real_lastName
0       Tom     Ju      NaN            Ju
1      Kity    NaN      Rob           Rob