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I have a table "DateTable" which has two columns:
A snippet of the table:
I set up the DateTable by creating a list of dates between the start and end date using List.Dates, converting it to a table, and then applying the following custom function to get the number of business days counting from the 01/03/2019:
(StartDate as date, EndDate as date) as number =>
let
ListDates = List.Dates(StartDate, Number.From(EndDate - StartDate), #duration(1, 0, 0, 0)),
RemoveWeekends = List.Select(ListDates, each Date.DayOfWeek(_, Day.Monday) < 5),
RemoveHolidays = List.RemoveItems(RemoveWeekends, #"bank-holidays-dl"),
CountDays = List.Count(RemoveHolidays)
in
CountDays
The function works as expected, however refreshing the data takes a long time. I was wondering if there could be any way to optimise this? Thank you!
Solved! Go to Solution.
The key to performance is to only calculate this column once instead of once for each row of your date table.
My approach would be to add an index column after filtering out weekends and holidays and then merge this back with the original dates.
let
StartDate = #date(2019, 3, 1),
EndDate = Date.From(DateTime.LocalNow()),
ListDates = List.Dates(StartDate, Number.From(EndDate - StartDate), #duration(1, 0, 0, 0)),
ListToTable = Table.FromList(ListDates, Splitter.SplitByNothing(), {"Date"}),
DateTable = Table.TransformColumnTypes(ListToTable, {{"Date", type date}}),
RemoveDays = Table.SelectRows(DateTable, each Date.DayOfWeek([Date], 1) < 5 and
not List.Contains(#"bank-holidays-dl",
AddIndex = Table.AddIndexColumn(RemoveDays, "Index", 1, 1, Int64.Type),
MergeQueries = Table.NestedJoin(DateTable, {"Date"}, AddIndex, {"Date"}, "RemovedDays", JoinKind.LeftOuter),
ExplandIndex = Table.ExpandTableColumn(MergeQueries, "RemovedDays", {"Index"}, {"WorkingDaysSinceStart"}),
SortRows = Table.Sort(ExplandIndex,{{"Date", Order.Ascending}}),
FillDown = Table.FillDown(SortRows, {"WorkingDaysSinceStart"})
in
FillDown
(StartDate as date, EndDate as date) =>
List.Accumulate(
List.Dates(StartDate, Duration.TotalDays(EndDate - StartDate), #duration(1, 0, 0, 0)),
0,
(s,c) => if Date.DayOfWeek(c, Day.Monday) >= 5 or List.Contains(#"bank-holidays-dl", c) then s else s+1
)
Thanks to the great efforts by MS engineers to simplify syntax of DAX! Most beginners are SUCCESSFULLY MISLED to think that they could easily master DAX; but it turns out that the intricacy of the most frequently used RANKX() is still way beyond their comprehension! |
DAX is simple, but NOT EASY! |
The key to performance is to only calculate this column once instead of once for each row of your date table.
My approach would be to add an index column after filtering out weekends and holidays and then merge this back with the original dates.
let
StartDate = #date(2019, 3, 1),
EndDate = Date.From(DateTime.LocalNow()),
ListDates = List.Dates(StartDate, Number.From(EndDate - StartDate), #duration(1, 0, 0, 0)),
ListToTable = Table.FromList(ListDates, Splitter.SplitByNothing(), {"Date"}),
DateTable = Table.TransformColumnTypes(ListToTable, {{"Date", type date}}),
RemoveDays = Table.SelectRows(DateTable, each Date.DayOfWeek([Date], 1) < 5 and
not List.Contains(#"bank-holidays-dl",
AddIndex = Table.AddIndexColumn(RemoveDays, "Index", 1, 1, Int64.Type),
MergeQueries = Table.NestedJoin(DateTable, {"Date"}, AddIndex, {"Date"}, "RemovedDays", JoinKind.LeftOuter),
ExplandIndex = Table.ExpandTableColumn(MergeQueries, "RemovedDays", {"Index"}, {"WorkingDaysSinceStart"}),
SortRows = Table.Sort(ExplandIndex,{{"Date", Order.Ascending}}),
FillDown = Table.FillDown(SortRows, {"WorkingDaysSinceStart"})
in
FillDown
This worked perfectly, thank you!
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