CODEWITHSUNDEEP
pandasdata-science
john
john

Reputation: 35390

How do I get the nth order # for a customer's purchase with pandas?

Let's say hypothetically I have a dataframe like this:

customer_id,purchase_date
A,2019-10-05
A,2019-10-02
A,2019-10-01
A,2019-10-03
B,2019-10-01
B,2019-10-03
C,2019-10-04

How do I generate a new column that shows the nth order progression for each customer so that I get a dataframe that looks something like this:

customer_id,purchase_date,order_num,
A,4
A,2
A,1
A,3
B,1
B,2
C,1

Upvotes: 2

Views: 109

Answers (1)

Quang Hoang
Quang Hoang

Reputation: 150745

You can do groupby().cumcount():

df['order_num'] = df.sort_values('purchase_date').groupby('customer_id').cumcount() + 1

Output:

  customer_id purchase_date  order_num
0           A    2019-10-05          4
1           A    2019-10-02          2
2           A    2019-10-01          1
3           A    2019-10-03          3
4           B    2019-10-01          1
5           B    2019-10-03          2
6           C    2019-10-04          1

Upvotes: 3

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