Coverage for jstark/features/earliest_purchase_date.py: 100%

1"""EarliestPurchaseDate feature""" 

2import pyspark.sql.functions as f 

3from pyspark.sql import Column 

4 

5from .min_feature import Min 

6 

7 

8class EarliestPurchaseDate(Min): 

9 def column_expression(self) -> Column: 

10 return f.to_date(f.col("Timestamp")) 

11 

12 @property 

13 def description_subject(self) -> str: 

14 return "Earliest purchase date" 

15 

16 def default_value(self) -> Column: 

17 return f.lit(None) 

18 

19 @property 

20 def commentary(self) -> str: 

21 return ( 

22 "Basically, when was a purchase first made. This could " 

23 + "be used to determine a whole myriad of useful information" 

24 + " such as when a customer first shopped, or" 

25 + "when a customer first bought a particular product. To make " 

26 + "use of this you would likely need to define " 

27 + "a large feature period, there isn't much use" 

28 + "in knowing when someone's earliest purchase was " 

29 + "in the previous two weeks." 

30 )