Pandas join DataFrame and Series over a column

Question

I have a Pandas DataFrame df that store a matching between a label and an integer, and a Pandas Series s that contains a sequence of labels :

print(df)

          label    id
0     AAAAAAAAA     0
1     BBBBBBBBB     1
2     CCCCCCCCC     2
3     DDDDDDDDD     3
4     EEEEEEEEE     4


print(s)

0        AAAAAAAAA
1        BBBBBBBBB
2        CCCCCCCCC
3        CCCCCCCCC
4        EEEEEEEEE
5        EEEEEEEEE
6        DDDDDDDDD

I want to join this DataFrame and this Series, to get the sequence of integer corresponding to my sequence s . Here is the expected result of my example :

print(df.join(s)["id"])

0        0
1        1
2        2
3        2
4        4
5        4
6        3

Answer 1

Use Series.map with Series :

print (s.map(df.set_index('label')['id']))
0    0
1    1
2    2
3    2
4    4
5    4
6    3
Name: a, dtype: int64

Alternative - be careful, if dupes no error but return last dupe row:

print (s.map(dict(zip(df['label'], df['id']))))