I want to calculate how many times each product was ordered each year but keep getting an error

user_16165572 0
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I am trying to count how many orders there was for each product, by using the line of code below

TSP_Order = TSP_Order.groupby(['ProdName','Year']).count('OrderID')

But i receive the error below

TypeError: count() takes 1 positional argument but 2 were given

An example of my dataset

ProdName OrderID Year
Toy Car 1 2015
Puzzle 1 2015
Toy Car 2 2015
Train Set 2 2015
Toy Car 3 2016
Puzzle 4 2016
Toy Car 5 2016
Train Set 5 2016

I want to calculate how many times each product was ordered per year.

pandas python
1 Answers

You were almost there. After grouping on the fields of interest, you need to access the column of interest, here OrderID, and perform the statistic you need (simple count in this case):

df.groupby(['ProdName','Year'])['OrderID'].count()

ProdName   Year
Puzzle     2015    1
           2016    1
Toy Car    2015    2
           2016    2
Train Set  2015    1
           2016    1
Name: OrderID, dtype: int64

with

df

    ProdName  OrderID  Year
0    Toy Car        1  2015
1     Puzzle        1  2015
2    Toy Car        2  2015
3  Train Set        2  2015
4    Toy Car        3  2016
5     Puzzle        4  2016
6    Toy Car        5  2016
7  Train Set        5  2016
user_140944600
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