how to merge multiple dataframes using pandas code example

Example 1: merge two dataframes based on column

df_outer = pd.merge(df1, df2, on='id', how='outer')

df_outer

Example 2: dataframe concatenate

# Pandas for Python

df['col1 & col2'] = df['col1']+df['col2']

#Output
#col1	col2	col1 & col2
#A1		A2		A1A2
#B1		B2		B1B2

Example 3: how to merge rows in pandas dataframe

df = dataframe.groupby(['date', 'sitename', 'name']).sum()