pandas group by and assign a group id then ungroup

Question

I have a large data set in the following format:

id, socialmedia
1, facebook
2, facebook
3, google
4, google
5, google
6, twitter
7, google
8, twitter
9, sn         


        

Answer 1

By using ngroup

df['grpId']=df.groupby(' socialmedia').ngroup().add(1)
df
Out[354]: 
    id  socialmedia  grpId
0    1     facebook      1
1    2     facebook      1
2    3       google      2
3    4       google      2
4    5       google      2
5    6      twitter      4
6    7       google      2
7    8      twitter      4
8    9     snapchat      3
9   10      twitter      4
10  11     facebook      1

---

Or pd.factorize and 'categroy'

df['grpId']=pd.factorize(df[' socialmedia'])[0]+1

df
Out[358]: 
    id  socialmedia  grpId
0    1     facebook      1
1    2     facebook      1
2    3       google      2
3    4       google      2
4    5       google      2
5    6      twitter      3
6    7       google      2
7    8      twitter      3
8    9     snapchat      4
9   10      twitter      3
10  11     facebook      1

---

df['grpId']=df[' socialmedia'].astype('category').cat.codes.add(1)
df
Out[356]: 
    id  socialmedia  grpId
0    1     facebook      1
1    2     facebook      1
2    3       google      2
3    4       google      2
4    5       google      2
5    6      twitter      4
6    7       google      2
7    8      twitter      4
8    9     snapchat      3
9   10      twitter      4
10  11     facebook      1