Create new fake data with new primary keys from existing dataframe python

I have a dataframe as following:

df1 = pd.DataFrame({'id': ['1a', '2b', '3c'], 'name': ['Anna', 'Peter', 'John'], 'year': [1999, 2001, 1993]})

I want to create new data by randomly re-arranging values in each column but for column id I also need to add a random letter at the end of the values, then add the new data to existing df1 as following:

df1 = pd.DataFrame({'id': ['1a', '2b', '3c', '2by', '1ao', '1az', '3cc'], 'name': ['Anna', 'Peter', 'John', 'John', 'Peter', 'Anna', 'Anna'], 'year': [1999, 2001, 1993, 1999, 1999, 2001, 2001]})

Could anyone help me, please? Thank you very much.

>Solution :

Use DataFrame.sample and add random letter by numpy.random.choice:

import string

N = 5
df2 = (df1.sample(n=N, replace=True)
          .assign(id =lambda x:x['id']+np.random.choice(list(string.ascii_letters),size=N)))
df1 = df1.append(df2, ignore_index=True)
print (df1)
    id   name  year
0   1a   Anna  1999
1   2b  Peter  2001
2   3c   John  1993
3  1aY   Anna  1999
4  3cp   John  1993
5  3cE   John  1993
6  2bz  Peter  2001
7  3cu   John  1993