I have a sales table with columns item
, week
, and sales
. I wanted to create a week to date sales column ( wtd sales
) that is a weekly roll-up of sales per item.
I have no idea how to create this in Python.
I'm stuck at groupby()
, which probably is not the answer. Can anyone help?
output_df['wtd sales'] = input_df.groupby(['item'])['sales'].transform(wtd)
As I stated in my comment, you are looking for cumsum()
:
import pandas as pd
df = pd.DataFrame({
'items': ['A', 'A', 'A', 'A', 'B', 'B', 'B', 'B'],
'weeks': [1, 2, 3, 4, 1, 2, 3, 4],
'sales': [100, 101, 102, 130, 10, 11, 12, 13]
})
df.groupby(['items'])['sales'].cumsum()
Which results in:
0 100
1 201
2 303
3 433
4 10
5 21
6 33
7 46
Name: sales, dtype: int64
I'm using:
pd.__version__
'1.5.1'
Putting it all together:
import pandas as pd
df = pd.DataFrame({
'items': ['A', 'A', 'A', 'A', 'B', 'B', 'B', 'B'],
'weeks': [1, 2, 3, 4, 1, 2, 3, 4],
'sales': [100, 101, 102, 130, 10, 11, 12, 13]
})
df['wtds'] = df.groupby(['items'])['sales'].cumsum()
Resulting in:
items weeks sales wtds
0 A 1 100 100
1 A 2 101 201
2 A 3 102 303
3 A 4 130 433
4 B 1 10 10
5 B 2 11 21
6 B 3 12 33
7 B 4 13 46
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