I have the following two dataframes:

   prod_id       land_ids
0  1             [1,2]
1  2             [1]
2  3             [2,3,4]
3  4             [1,3]
4  5             [3,4]

   land_id       land_desc
0  1             germany
1  2             austria
2  3             switzerland
3  4             italy

Bascially, I want all numbers in column land_ids to individually join the other df.

The result should look something like this:

   prod_id       land_ids  list_land
0  1             [1,2]     germany austria
1  2             [1]       germany
2  3             [2,3,4]   austria switzerland italy
3  4             [1,3]     germany switzerland
4  5             [3,4]     switzerland italy

Preferrably, the column list_land is one string where the lands are concatenated. But I would also be fine with getting a list as a result.

Any idea on how to do this?

Here is my code for creating the df:

data_prod = {'prod_id': [1,2,3,4,5], 'land_ids': [[1,2],[1],[2,3,4],[1,3],[3,4]]}
prod_df = pd.DataFrame(data_prod)

data_land = {'land_id': [1,2,3,4], 'land_desc': ['germany', 'austria', 'switzerland', 'italy']}
land_df = pd.DataFrame(data_land)

>Solution :

you can use the apply method:

prod_df['list_land'] = prod_df['land_ids'].apply(lambda x: [land_df.loc[land_df['land_id'] == y]['land_ids'].values[0] for y in x])

In this case, the list_land column is a list. You can use the following code if you want it to be a string.

prod_df['list_land'] = prod_df['land_ids'].apply(lambda x: ' '.joind([land_df.loc[land_df['land_id'] == y]['land_ids'].values[0] for y in x]))