Prompt
Answer
Data Transformation: Adding Business Days Excluding Holidays in Power Query
Problem Analysis
Transforming date-related data to account for business days while excluding holidays is a common issue in data analysis. This task involves:
- Adding a specified number of business days to a given date.
- Ensuring that weekends and holidays are excluded from the calculation.
Solution Outline
To address this problem in Power Query, we will:
- Create a list of dates accounting for business days.
- Exclude weekends from this list.
- Exclude specified holidays from the final date list.
- Create a custom function in M language to add business days.
Steps and Explanation
1. Create a List of Dates
Generate a list of dates starting from the given date and extending for the required number of days.
let
StartDate = #date(2023, 10, 9),
NumberOfDays = 30,
DateList = List.Dates(StartDate, NumberOfDays, #duration(1, 0, 0, 0))
in
DateList
2. Exclude Weekends
Filter out weekends from the DateList
.
let
StartDate = #date(2023, 10, 9),
NumberOfDays = 30,
DateList = List.Dates(StartDate, NumberOfDays, #duration(1, 0, 0, 0)),
BusinessDays = List.Select(DateList, each Date.DayOfWeek(_, Day.Monday) < 5)
in
BusinessDays
3. Exclude Holidays
Assume we have a list of holidays. We will exclude these from our BusinessDays
list.
let
StartDate = #date(2023, 10, 9),
NumberOfDays = 30,
DateList = List.Dates(StartDate, NumberOfDays, #duration(1, 0, 0, 0)),
BusinessDays = List.Select(DateList, each Date.DayOfWeek(_, Day.Monday) < 5),
Holidays = {
#date(2023, 10, 10),
#date(2023, 10, 20)
},
BusinessDaysExcludingHolidays = List.Difference(BusinessDays, Holidays)
in
BusinessDaysExcludingHolidays
4. Custom Function to Add Business Days
Create a custom M function to add a specified number of business days to a start date, excluding weekends and holidays.
// Function Definition
let
AddBusinessDays = (startDate as date, daysToAdd as number, holidays as list) as date =>
let
DateList = List.Dates(startDate, daysToAdd + 60, #duration(1, 0, 0, 0)), // Adding buffer
BusinessDays = List.Select(DateList, each Date.DayOfWeek(_, Day.Monday) < 5),
BusinessDaysExcludingHolidays = List.Difference(BusinessDays, holidays),
ResultDate = List.FirstN(BusinessDaysExcludingHolidays, daysToAdd){daysToAdd - 1}
in
ResultDate
in
AddBusinessDays
// Usage Example
let
StartDate = #date(2023, 10, 9),
DaysToAdd = 15,
Holidays = {
#date(2023, 10, 10),
#date(2023, 10, 20)
},
Result = AddBusinessDays(StartDate, DaysToAdd, Holidays)
in
Result
Promoting Best Practices
- Modular Functions: Break down complex operations into modular functions for better readability and maintenance.
- Error Handling: Implement error handling to deal with unexpected values or situations.
- Reusable Code: Create reusable functions to save time on recurring tasks.
Further Learning
For a deeper understanding of Data Transformation and more advanced techniques, consider the courses offered on the Enterprise DNA Platform.
By following this structured approach, you can effectively add business days to a date in Power Query, excluding weekends and holidays. This method ensures accuracy and efficiency in handling date-related transformations.
Description
This guide outlines a method to add business days to a date in Power Query while excluding weekends and specified holidays, featuring M language code and best practices for modular functions and error handling.