replace column values in one dataframe by values of another dataframe

Question

I have two dataframes , the first one has 1000 rows and looks like:

Date            Group         Family       Bonus
2011-06-09      tri23_1       Laavin             


        

Answer 1

This is an old question but here is another way to do it, it is not like the pandas way but is fast

Reproducing the dataframe 1 - this is to be updated

df_1

    Date    Group   Family  Bonus
0   2011-06-09  tri23_1     Laavin  456
1   2011-07-09  hsgç_T2     Grendy  679
2   2011-09-10  bbbj-1Y_jn  Fantol  431
3   2011-11-02  hsgç_T2     Gondow  569

Reproducing dataframe 2 - the look up

df_2

    Group   Hotel
0   tri23_1     Jamel
1   hsgç_T2     Frank
2   bbbj-1Y_jn  Luxy
3   mlkl_781    Grand Hotel
4   vchs_94     Vancouver

Get all the hotel id (key column) from the dataframe 1 as a list

key_list = list(df_1['Group'])

['tri23_1', 'hsgç_T2', 'bbbj-1Y_jn', 'hsgç_T2']

Create a dictionary from the look up dataframe which has the key col and the value col

dict_lookup = dict(zip(df_2['Group'], df_2['Hotel']))

{'bbbj-1Y_jn': 'Luxy',
 'hsgç_T2': 'Frank',
 'mlkl_781': 'Grand Hotel',
 'tri23_1': 'Jamel',
 'vchs_94': 'Vancouver'}

Replace the value by creating a list by looking up the value and assign to dataframe 1 column

df_1['Group'] = [dict_lookup[item] for item in key_list]

Updated dataframe 1

    Date    Group   Family  Bonus
0   2011-06-09  Jamel   Laavin  456
1   2011-07-09  Frank   Grendy  679
2   2011-09-10  Luxy    Fantol  431
3   2011-11-02  Frank   Gondow  569