dataframe left join two dataframes code example

Example 1: python: left join

new_df = df_1.merge(df_2, on='id', how='left', indicator=True)

Example 2: pandas merge multiple dataframes

import pandas as pd
from functools import reduce

# compile the list of dataframes you want to merge
data_frames = [df1, df2, df3]
df_merged = reduce(lambda  left,right: pd.merge(left,right,on=['key_col'],
                                            how='outer'), data_frames)