Pandas concat function with count assigned for each iteration

Question

At the replication of a dataframe using concat with index (see example here), is there a way I can assign a count variable for each iteration in column c (where column c is the count variable)?

Orig df:

	a	b
0	1	2
1	2	3

df replicated with pd.concat[df]*5 and with an additional Column c:

	a	b	c
0	1	2	1
1	2	3	1
0	1	2	2
1	2	3	2
0	1	2	3
1	2	3	3
0	1	2	4
1	2	3	4
0	1	2	5
1	2	3	5

This is a multi-row dataframe where the count variable would have to be applied to multiple rows.

Thanks for your thoughts!

Answer 1

You could use np.arange and np.repeat:

N = 5
new_df = pd.concat([df] * N)
new_df['c'] = np.repeat(np.arange(N), df.shape[0]) + 1

Output:

>>> new_df
   a  b  c
0  1  2  1
1  2  3  1
0  1  2  2
1  2  3  2
0  1  2  3
1  2  3  3
0  1  2  4
1  2  3  4
0  1  2  5
1  2  3  5