Is there a function in python to number the time an item appears in the dataframe?

Question

I am trying to check when a client appears in my dataframe to do some logic with other results. However, I am unable to number when the customer appears. I've gotten the first and last time it appears, I just can't get it in the intervals between the first and last time. Could you please help me? Here is an example table, I want column C as the result.

Date    Customer    Appear
01/01/2021  A   1
01/01/2021  B   1
01/01/2021  C   1
01/02/2021  A   2
01/02/2021  B   2
01/02/2021  C   2
01/03/2021  A   3
01/03/2021  B   3
01/03/2021  C   3
01/04/2021  A   4
01/04/2021  B   4
01/05/2021  A   5
01/05/2021  B   5
01/06/2021  A   6

Use `df['Appear'] = df.groupby('Customer').cumcount().add(1)` — mozway, Feb 09 '22 at 15:02

score 1 · Answer 1 · answered Feb 09 '22 at 15:03

1

You can try with groupby with cumcount

df['new'] = df.groupby('Customer').cumcount()+1
Out[202]: 
0     1
1     1
2     1
3     2
4     2
5     2
6     3
7     3
8     3
9     4
10    4
11    5
12    5
13    6
dtype: int64

answered Feb 09 '22 at 15:03

BENY

317,841
20
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ouch, it is not for answer... – jezrael Feb 09 '22 at 15:03
its work, like @mozway post: df['Appear'] = df.groupby('Customer').cumcount().add(1) – haraujo Feb 09 '22 at 16:02

Is there a function in python to number the time an item appears in the dataframe?

1 Answers1