Map values from lists in one Dataframe to unique values in another

Question

I have 2 dataframes, one containing some unique values, and another one containing unique groups of this unique values, with group ids, where each value appears in one group and one group only.

df1:         df2:
                groups    ids
0  A        0 (A, D, F)    1
1  B        1 (C, E)       2
2  C        2 (B, K, L)    3
3  D         .
.            .
.
.             

Is there an efficient way to map values from the first dataframe with ids from the second? I got the result using 2 for loops but it is very slow, and tried using 'np.where(df1 in df2["groups"])', but got an array of None.

Desired output:

df3:
       id
0  A    1
1  B    3
2  C    2
3  D    1
.
.
.

Answer 1

If in column groups are tuples use:

s = df2.explode('groups').set_index('groups')['ids']
df1['id'] = df1['col'].map(s)

Answer 2

temp_df2 = df2.set_index('ids')['groups'].apply(pd.Series).unstack().reset_index(name=1).drop('level_0',1)

df.merge(temp, on=1).drop(['level_0'],1)

Output

   1  ids
0  A    1
1  B    3
2  C    2
3  D    1