pandas series.fillna() code example
Example 1: dataframe fillna with 0
df['column'] = df['column'].fillna(0)
Example 2: python fillna with mean in a dataframe
df["newColumName"] = df["originalColumnName"].fillna(df["originalColumnName"].mean())
df['column'] = df['column'].fillna(0)
df["newColumName"] = df["originalColumnName"].fillna(df["originalColumnName"].mean())